Intro: Under Cover

This rules nugget looks at two separate but complementary items: the very simple interaction between a shield and its wielder's size, and the more involved matter of letting shields provide cover instead of a DB bonus. I've got some old rules online:

http://www.gamesdiner.com/gurps/GULLIVER/B5combat.htm#SizeShields

I inserted some quick thoughts on a 4e update in a SJG forum thread:

http://forums.sjgames.com/showthread.php?p=461327#post461327

Below is a more thorough attempt at 4e-friendly rules.

Size and shields

Wielder size

For a shield of a given size, protection offered is relative to the wielder's size. Subtract user SM from shield DB.

Example: A human small shield (DB 1) repurposed for a SM -2 Halfling covers much of the little fellow, and offers DB 3. A shield of that size in the mitt of a SM 1 or larger Giant, however, would offer no real protection and no DB.

The above assumes that the shield's straps/grips are sized for the wielder. If the Halfling or Giant were to pick up an actual human's shield, apply skill penalties (or disallow use) for poor fit.

If wielder size brings a shield's DB to exactly 0, assume he can still use it to Block using Shield skill, though with no DB. The shield cannot be used to Block if the wielder is any larger.

Wielder position

Kneeling, sitting, or lying down behind a shield adds 1 to DB – a useful bonus, but with potential drawbacks (below).

Crouching adds 1 to DB if the wielder wishes; he can take the extra protection, or forego it if it would trigger drawbacks.

"Hunkering down" behind a shield – squatting or kneeling with head down, making yourself as small as possible – adds 2 to DB, but makes the wielder immobile: no movement, attacks or Active Defense. The cover provided is generally not worth the risk, unless it provides full cover (below).

Large shield drawbacks

A large enough shield gets in the wielder's own way, or becomes too clumsy to wield effectively. Apply the following for final DB (after modification for size and position):

A shield with DB 3 hampers the wielder's melee attacks, for -2 TH (B547, under "Attacker's Situation).

A shield with DB raised to 4 becomes even more troublesome if used actively: apply a -2 on all combat skills (not just melee TH), which applies -1 to Parry and Block as well. Also apply -2 to Vision rolls and -1 to Dodge.

A shield with DB raised to 5 or more is too large to be used actively; it allows no Active Defense, and would hamper any other actions seriously as well (GM call). It can be used instead for full cover (below).

Shields and cover

In general, treat shields as offering only their DB, per written rules. But whenever the GM thinks it sensible, treat shields as cover instead. (See general rules for cover on B407).

A shield protects with either its cover (see effects below) or its DB, not both at once. When an attack treats a shield as cover, the shield wielder can attempt any normal defense, even a Block, but does so without the added bonus of DB.

Here are three options for gaming protection from cover:

Abstract cover

For simplicity, use shield DB as a TH penalty versus any location on the target; don't worry about specific effects by location. If the TH penalty causes the attack to fail, the attack struck the shield, with no additional action on the part of the defender. If the attack succeeds, it will strike an area not covered by the shield.

Example: You hold a shield with DB 3. Treating this as cover, enemy attacks take -3 to hit you, regardless of what location they target. An attack that fails by 1 to 3 strikes the shield.

Random cover

Per B408, you can give attacks a random chance of striking cover: half cover, instead of a -2 TH penalty, applies a 50/50 chance (4-6 on 1d6) that the attack will hit the cover.

Here's an expansion of that:

No cover: Doesn't significantly hide target. No effect.
Slight cover: Hides 1/3 or less of the target. Treat as -1 TH, or as 2 in 6 chance of striking cover. Example: DB 1 shield.
Half cover: Hides about 1/2 of the target. Treat as -2 TH, or as 3 in 6 chance of striking cover. Example: DB 2 shield.
Good cover: Hides 2/3 to 3/4 of target. Treat as -3 TH, or as 4 in 6 chance of striking cover. Example: DB 3 shield.
Excellent cover: Hides most of target. Treat as -4 TH, or as 5 in 6 chance of striking cover. Example: DB 4 shield.
Full cover: Hides all of target. Example: DB 5+ shield.

Specific cover

Specific hit locations gain full, half, or no cover from the shield. Full cover makes a hit location impossible to hit. Treat half cover as above. Locations not mentioned (e.g., face) gain no cover and can be targeted at their usual penalty.

DB 1: Half cover for shield arm/hand (full cover for shield hand if buckler), torso/vitals/groin.
DB 2: Full cover for shield arm/hand; half cover for torso/vitals/groin.
DB 3: Full cover for shield arm/hand, torso/vitals/groin; half cover for legs (but not feet).
DB 4: Full cover for shield arm/hand, torso/vitals/groin, legs (but not feet).
DB 5+: See Full Cover below.

Specific cover means that an attack need only target an uncovered location – such as the weapon arm, at no penalty beyond the usual -2 – to negate shield DB. On the other hand, some locations become completely covered, disallowing attack. Overall, specific cover provides a fair tradeoff compared to the abstract and random treatments.

Full Cover

While a defender cannot actively wield a shield with DB of 5 or more, he can hide behind it to gain full cover for all hit locations. As above, this means the locations cannot be hit.

DB 5 barely covers the defender. It provides full cover from the front center hex only, and the defender must remain still. Attacks from the left/right front hexes, lobbed attacks, or any shield wielder movement render cover incomplete: treat as excellent cover (-4 TH, or 5 in 6 chance of striking cover).

DB 6 allows full cover from any front hex and even allows minimal wielder movement behind the shield. (Whether and how the wielder can prop up such a huge shield in the first place is a GM call.)

At DB 7 and larger, we're essentially talking propped-up walls behind which the defender has plenty of room to move. Handle accordingly.

The GM will rule on any special considerations. A melee fighter could run behind a covering shield to get at the defenseless wielder – or possibly even reach his weapon over the top of the shield from the front. A very small fighter behind a large propped-up shield may have full cover versus enemy shooters, with room to move about too – but if he pops out from behind cover to return fire, he'll be partially exposed in that instant. And so on.

Protection and facing

Per written rules, a shield offers protection only versus attacks from the wielder's front center hex and shield-side hex. It provides no protection – DB or cover – vs attacks from the weapon-side hex, side hexes, or rear hex.

An exception: As described above, DB 5 and larger shields used as full cover can provide full or partial cover from all three front hexes.

When to use it

GM choice

When does a shield provide DB, and when does it provide cover? It's a GM call. There's nothing particularly wrong with the existing rules for shields and DB, but cover may play more realistically in some situations.

For example, using the specific cover rule, you may find it more realistic for a shield to provide great protection to the torso and partial protection to the legs, while leaving the head or feet fully exposed, instead of granting equal protection to all locations.

If you don't care for a wholesale switch to shields as cover, you might use the rules in limited instances. The full cover rules come in particularly handy when a character wants to curl up behind a shield – it's a great defense versus ranged attacks from arrows to dragon fire.

Another good use for the rules is any instance in which a shield user has no active defense versus a ranged attack. Currently, even a large shield offers no protection against an unseen arrow, as it only aids in active defense. Cover rules allow a chance for passive protection too.

Example: A silent crossbow bolt streaks toward an unsuspecting knight with a DB 2 shield. Whether the arrow intentionally or randomly targets a specific hit location, the attack suffers a -2 TH (using abstract cover), or has a 50/50 chance of striking the shield (using random cover), or attacks the head normally, the torso with partial cover, and the shield arm with no chance of avoiding the shield (specific cover). Although the knight has no Active Defense, the shield may catch the missile.

Attacker choice

Optionally, an attacker can choose to treat a shield as cover. He's specifically aiming to strike far from the shield's protected areas, negating its extra protection. Using abstract cover, that means an overall TH penalty. Using random cover, he takes no TH penalty, but stands a random chance of striking the shield. Using specific cover, he'll have to choose a hit location that's not fully covered.

If the attacker hits, follow rules as above: the defender can defend (and even Block) normally, but gains no DB.

Status

My old 3e rules worked fine for me, but this is an all-new update for 4e. It needs scrutiny and testing!

Designer's notes

1. If the GM allows fighters the choice of whether to handle shields as DB or as cover, my earlier rules suggested that either the attacker or defender could make the choice. I removed the defender choice for this update; it seems more sensible that the attacker would be the one to decide, by choosing to expressly aim for uncovered areas. What do you think?

2. While we're on that topic: It would make sense that an attacker is always trying to strike somewhere unprotected by the shield, not making a special choice to do so. But since there's no default TH difference between hitting a shield-protected target and an unprotected one, we can assume that the default blow isn't a particularly concerted effort to do so. The above penalized blow does mark a concerted effort to get around the shield, whatever exactly that may mean in the abstract positioning of combat.

The ruling seems even more sensible in the case of ranged combat: either you aim a shot at the target in general, in which case you might send your arrow directly into his shield; or you deliberately aim for some smaller, unprotected part. The latter is a tougher shot, but unless the target responds with a skillful Block, a successful hit guarantees you're not haplessly plunking your missile into that darned buckler.

3. These rules let you treat a shield as cover, and optionally let an attacker bypass that cover (i.e., negate the shield's DB) by taking a TH penalty. That all plays nicely with 4e's written rules for cover.

But the net effect of bypassing DB by taking an equivalent TH penalty (or by aiming at an unprotected area, depending on how you play it) bumps up against one other rule: the Deceptive Attack. That action could also be employed to simulate "bypassing" shield DB – but it would charge double DB as a TH penalty.

That had me thinking: Should these rules use double DB as the TH penalty for cover? Doing so would put things in line with the Deceptive Attack rules, yes – but would then conflict with the rules for cover. A half-covered target only applies a -2 TH in 4e, which seems to play nicely with the game's 3d hit probabilities as well. Using doubled DB as a cover penalty would imply that a small DB 1 shield or cloak covers half of a human, and that medium or large shields cover almost all of a person. That doesn't seem right.

In the end, I favored conformance with the cover rules, as cover is the topic at hand. Yes, this means that if the GM allows you to treat a target's shield as cover, you can essentially take a "cheap" Deceptive Attack at only -1 TH per -1 Active Defense, up to the target's DB (further decreases in Active Defense would carry the usual TH cost). That marks a break from standard treatment of Deceptive Attack to reduce defenses.

That's using abstract cover, though. I think specific cover plays more nicely with Deceptive Attack. You can avoid DB entirely just by attacking an unprotected location, but on the other hand, some locations will be fully protected; you can't attack them at all. It makes for a different dynamic.

The GM could then allow Deceptive Attack, at the full -2 TH x shield DB, as a difficult way of getting at the fully protected targets – say, a sword thrust from above that goes over and behind the top of a large shield, to get at the (normally) fully-covered vitals. That preserves a special role for Deceptive Attack as a way of getting past shield protection. It's a thought, anyway; it should be rigorously tested.

Wrapping Up

The above offers a lot of shield stuff for the GM toolbox, but there are decisions: when to treat shields as cover instead of DB, and which treatment of cover to use (abstract, random, or specific).

What looks useful, not-so-useful, or just plain broken in there?