I'd say do what Dev said. but maybe with L33tz4n moving NW, N instead.

What Dev said but with L33tz4n moving NW N instead:

Fawriel: Defend.
L33tz4n: NW, N. Summon Enchantresphere N of Ice Serpent.
Enchantresphere: Attack Ice Serpent.


Although, if we all attacked it right away we could just get rid of it in two turns, before the wall is down:

Fawriel: Attack Ice Serpent.
L33tz4n: Summon Enchantresphere N of Ice Serpent, Attack Ice Serpent.
Enchantresphere: Attack Ice Serpent.

Then once it's down we could summon up some more stuff, and wait for the next part of the battle.


Edit: For the second plan, L33tz4n would take double-damage, but it's only four. The AWA could heal it all back on the next turn anyways.