Simple D&D melee stunts

House rule for simple melee combat stunts in a D20 system. After making the attack roll:

Succeed: Disadvantaged damage and stunt, or normal damage.

Succeed by 5: Normal damage and stunt, or advantaged damage. Succeed by 10 (crit): Advantaged damage and stunt, or doubled damage.

Fail: No effect. Fail by 5: Take disadvantaged damage from opponent. Fail by 10 (fumble): Take normal damage from opponent. Bosses (and PCs) could deal disadvantaged damage and a stunt instead.

Advantaged roll: Roll two dice, take the better. Disadvantaged roll: Roll two dice, take the worse.

Bonus idea: armor damage reduction

If you want armor to reduce damage instead of (or in addition to) making the target harder to hit, do not use a static number for the armor. Roll for it, just like for the weapon damage. Shields add an extra armor roll. (Shields should be more useful in games than they usually are.)

Option 1 (math, less deadly): Subtract the armor roll from the weapon roll. If the armor equals or exceeds the weapon, no damage is taken.

Option 2 (no math, more deadly): Compare the rolls. If the weapon roll is higher, the target takes the damage.

If you really want to get crunchy with this, you could add skill dice to either or both sides of the combat. Add terrain and range dice for defending against a ranged attack. Use your imagination. You could even use this system in place of making separate attack and damage rolls. (h/t: Into The Odd)