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War Caster

Complete guide to the War Caster feat in D&D 5e. Master spellcasting in armor, maintain concentration under fire, and punish enemies with spell opportunity attacks.

Prerequisite: The ability to cast at least one spell

Benefit

You gain advantage on concentration saves, can perform somatic components with weapons or shields, and can cast spells as opportunity attacks.

Mechanics

War Caster provides three benefits crucial for front-line spellcasters: **Advantage on Concentration:** You have advantage on Constitution saving throws that you make to maintain concentration on a spell when you take damage. **Somatic Components with Full Hands:** You can perform the somatic components of spells even when you have weapons or a shield in one or both hands. **Spell Opportunity Attack:** When a hostile creature's movement provokes an opportunity attack from you, you can use your reaction to cast a spell at the creature, rather than making an opportunity attack. The spell must have a casting time of 1 action and must target only that creature. **Important Details:** - Concentration advantage stacks with other sources of advantage - The somatic component benefit allows shield + weapon spellcasting - Spell opportunity attacks can use any single-target spell (Booming Blade, Inflict Wounds, etc.) - You still need a free hand for material components if they have a cost - The spell must target only that creature (no AoE spells)

Synergies

*Resilient (Constitution) feat - Proficiency in CON saves plus advantage makes concentration nearly unbreakable
*Cleric/Paladin builds - Cast while using shield and weapon without War Caster component pouches
*Booming Blade/Green-Flame Blade cantrips - Excellent spell opportunity attacks with rider damage
*Polearm Master - Trigger opportunity attacks when enemies enter reach, then cast at them
*Sentinel feat - Lock down enemies and cast spells when they try to escape
*Bladesinger/Eldritch Knight/Swords Bard - Essential for gish builds
*Counterspell - More concentration saves passed means keeping your spells active

Common Mistakes

Common Mistake

Thinking you need War Caster to cast with a shield - you only need it if you can't use a component pouch or focus

Common Mistake

Forgetting the spell opportunity attack must target only that creature

Common Mistake

Not realizing spell opportunity attacks use spell slots

Common Mistake

Using AoE spells for opportunity attacks - they must be single-target

Common Mistake

Forgetting you still need material components with a cost

Common Mistake

Not utilizing the spell opportunity attack feature - it's incredibly powerful

DM Tips

DM Tip

War Caster makes concentration spellcasters much harder to disrupt

DM Tip

Spell opportunity attacks can be devastating - Inflict Wounds as a reaction is brutal

DM Tip

This feat is essential for gish builds to function properly

DM Tip

Consider that War Caster users can lock down areas with reach + spell attacks

DM Tip

Multiple small hits are better for breaking concentration than one big hit

DM Tip

Counterspell and Dispel Magic still work against War Caster users

DM Tip

This feat makes front-line clerics and paladins significantly more durable

Sources & Further Reading

War Caster — D&D 5e Wikidot — Full SRD feat text
Feats — D&D Beyond — Official feat list

War Caster

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Benefit

Mechanics

Synergies

Common Mistakes

DM Tips

Sources & Further Reading