frostmephit ability: "An enemy unit that targets FrostMephit with any attack or ability is frozen for 1 turn.
Immune to Freeze."
behemoth ability: "Cannot be targeted by enemy minions."
gravitymage is frozen even though it targeted an empty location. i guess this implies that the teleported unit is targeted.
since it should be a target by frostmephit-gravitymage interaction, not sure why nexus can teleport behemoth.
between these two, I think the gravitymage version makes the most sense,
so maybe I'll finally change the nexus/portal behemoth thing.