From DDO wiki
Guards are effects can trigger when you are a target of an attack (they happen on being hit). The effects vary.
- Some guards trigger with 100% probability (always), some trigger more rarely.
- Some guards cannot proc again immediately; one must wait x seconds before next proc.
- Being hit by a melee attack
- Being hit by ranged attack
- Being hit by a spell
Target of the guard effect
- The character being hit
- The attacker
- All enemies around defender
Effects are very different:
- Attackers are usually dealt damage in return (for example Legendary Bracers of the Sun and Moon), or are a target of some debilitating effect (Radiance Guard)
- Defenders usually receive a buff (for example Earthen Guard, temporary HP, or minor heal
Sources of guard effects