I'd love to have something along the lines of a BLM ley-lines or arcanist-Shadowflare.

Geomancer would definitely a lay-down ability/standing in type of mechanic

Which if the geomancer stands in- would grant small dmg mitigation buff on GEO or add a condition on a specific ability (a damage and/or a heal). Similar to Noct-sect AST.

If you move outside that layed-down buff or recently moved out (push out) you gain a temporary-different buff (Wind thematic). Maybe a self movement speed or a Diurnal Sect AST regen or dot on an ability.

(Water thematic)
I can also see something along the lines of a fluid wall cast, that if you move through would give you a bubble(shield-mitigating dmg) it would be a pretty cool engaging-boss ability.