Engulfing Slagwurm

Whenever this creature blocks or becomes blocked by a creature, destroy that creature. You gain life equal to that creature's toughness.

General Marhault Elsdragon

Whenever a creature you control becomes blocked, it gets +3/+3 until end of turn for each creature blocking it.

Other Elves you control get +1/+1.
Whenever you cast an Elf spell, you may pay {G}. If you do, draw a card.

Other Elf creatures you control get +1/+1.
{T}: Add {G} for each Elf you control.

All creatures able to block this creature do so.

Enchant creature
All creatures able to block enchanted creature do so.