Icy Fortitude. If damage reduces the zombie to 0 hit points, the zombie elf explodes and hits everything in a 5 foot radius with ice shards. Anyone in the area must make a DC12 Dexterity saving throw or be hit with 1d6 piercing damage (Hit: 4) and 1d4 cold damage (Hit: 2). 

The Zombie elf makes two attacks on its turn: one Icy Slam attack, and one Bite attack.

Icy Slam. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 4 (1d6 + 2) bludgeoning damage and 2 (1d4) cold damage.

Bite. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 4 (1d6 + 2) piercing damage and will have to make a DC10 Constitution Saving throw or become poisoned.