Yoshi-P: "If you want more engaging content, go play Ultimate"

[ty_taurus]

I'm throwing in my guess as a Eukrasian Phelgma, lower damage but with debuff.

See, I get the vibe it’s a really hard hitting attack. The visual effect is huge, and the way the sage just pushes down gives me this “with all my strength” type of vibe.

[Mimilu]

My thoughts/guesses:

SGE: I think I could hear the debuff/DoT sound, so my guess is an AoE DoT. Maybe it's getting WHM's old Aero III to try and push the "DPS-Healer" angle more? (◍´͈ꈊ`͈◍)
AST: Those are Horoscope's sounds effects, aren't they? Maybe it's an upgraded/changed version of Horoscope? You can even see the effects going off on the surrounding partymembers afterwards.
WHM: Looks like an AoE lily burst heal to me. I think I can even hear the burst heal sound effect.
SCH: I'll agree with everyone else and say that I think it's an AoE Chain Stratagem.

[Absurdity]

See, I get the vibe it’s a really hard hitting attack. The visual effect is huge, and the way the sage just pushes down gives me this “with all my strength” type of vibe.

Watch it end up just being Dyskrasia III