To claim total cover from a tower shield, you must use a standard action. The tower shield rules don’t say that, but that’s what they mean. Since you can take only one standard action each round, you cannot also attack, cast a spell, activate a magic item (except for some use-activated items), use a special ability, use total defense, or start or complete a full-round action during the same round you claim total cover from the shield. You can, however, take a move action before or after you claim cover from the shield.
Like other kinds of cover, the shield has to have a location relative to you on the battlefield. When you use the shield for cover, choose one edge of your space (not a corner). You have total cover against any attack’s line of effect that passes through that side of your space. If an attack’s line of effect goes through the corner of the side of your space that the shield blocks, you get cover from the shield (+4 AC, +2 on Reflex saves) instead of total cover. If an attack’s line of effect passes through a side of your space that the shield does not block, you get no cover from the shield at all. To determine where the line of effect enters your space, draw a line from the attacker’s center to your center. Or, in the case of a magical effect, from the effect’s point of origin and your center.
Once you claim cover from the shield, the shield keeps blocking the side of your space that you chose until the beginning of your next turn, when you can again decide whether you’ll use the shield for cover. Once you choose the side of your space that the shield blocks, you cannot change it until your next turn.
You continue to threaten the area around you while you use the shield for cover; however, it provides your opponents with the same benefits you get. You cannot make attacks through the side of your space that the shield blocks, and should you attack through the corners of that space, your foe gets cover against your attack. Since cover of any kind prevents attacks of opportunity (see page 151 in the Player’s Handbook), the shield keeps you from making attacks of opportunity in a pretty wide swath.
Total cover or cover from a tower shield has the following effects in different situations:
- Magical Attacks: A tower shield’s effects on magical attacks depend on the kind of magical attack. Any attack aimed at your equipment is aimed at you. If a magical attack has you as a specific target (that is it does not merely affect the area that contains you but is aimed right at you), the shield has no effect. All rays fall into this category, as does any spell that has a Target entry in its header and any spell that has an Effect entry and affects creatures (provided, of course, that the attacker can and does choose the shield user as a target). Magical attacks that fill areas (bursts, cones, cylinders, lines, emanations, and spreads) are subject to all the rules for cover on page 151 of the Player’s Handbook. Such attacks are completely blocked if line of effect between you and the attack’s point of origin passes through the side of your space the shield blocks. You get cover (+4 AC, +2 on Reflex saves) if the magical attack’s line of effect passes through the corner of the blocked side. Spread effects reach around the shield if they normally would extend into your space, but you still get a Reflex save bonus for cover when they do. A gaze attack is blocked if the shield would give you total cover against attacks from the creature with the gaze attack. If the shield gives you cover only, you’re still subject to the gaze attack (although you could avert or close your eyes to avoid the attack).
- Attacks of Opportunity: As noted earlier, cover or total cover prevents attacks of opportunity. So you could, for example, hunker down behind a tower shield and pick up a weapon or rummage around in a backpack and avoid attacks of opportunity against you. If you’re moving while using the shield for cover, things get a little more complicated. You must determine whether the shield gives you cover (or total cover) at the point during your movement when you’d normally provoke an attack of opportunity. Remember that attacks of opportunity are usually resolved before the actions that provoke them. In many cases, the shield won’t be positioned correctly to protect you during your whole move.
- Charging and Bull Rushing: Opponents can charge you while you claim cover from the shield. An opponent moves as normal when charging you, moving to the closest square from which a melee attack normally would be possible. If the shield gives you total cover from the attack, the attack automatically fails. Foes can bull rush you normally, moving right into your space in spite of the shield. You normally get an attack of opportunity against someone entering your space, but not if the shield gives your foe cover or total cover.
- Grapple and Snatch Attacks: Total cover from a tower shield blocks such attacks (the foe just can’t get hold of you). The foe could, however grab the shield. Conduct such attacks just like any other grapple or snatch attack. Your foe can’t damage you unless he pins you first. You can escape the foe’s hold simply by dropping the shield (a standard action since it’s strapped to your arm), so long as the foe has not pinned you.
- Traps: Cover or total cover from a tower shield is just as effective against a trap as it is against any other attack.
