Dire Acorn (3.5e Monster)

You see an acorn fall like lightning on your friend, and he falls like a dead companion on the ground.

See Acorn.

Combat
Drop Like a Bullet in the Dark: If a dire acrorn exceeds his target's AC on its attack by 5 or more, that target makes a DC 60 Fortitude save or dies.

Uncanny Resilience: If a dire acorn is dealt damage to, it only takes half of the damage remaining after DR is factored in.