List of Abilities which DO NOT work in PVP.

[SuperZay]

Also,
Cleric Stance
Invigorate
Army's Paeon
Goad
Summon II/Titan-Egi (who'd use it over Gardua/Ifrit)?
Decimate (who'd use it over Fell Cleave)?

[Februs]

Also,
Cleric Stance
Invigorate
Army's Paeon
Goad
Summon II/Titan-Egi (who'd use it over Gardua/Ifrit)?
Decimate (who'd use it over Fell Cleave)?

Since when?

These might not have a commonly needed, but I don't recall them being useless. Triple Decimate + Bloodbath + Vengence + Push back is, quite possibly, the biggest self-hp return a War can get. The odds of you using it in Feast is low, as the number of players is smaller, but in Frontlines? Different story. Double/Triple Decimates on top of nodes was a pretty common tactic back in the day. War's could practically soak up any amount of damage if they did it right, as well as provide a tremendous amount of AoE pressure on enemy healers.

Invig, Paeon, and Goad have seen dramatically diminished returns since Sprints Tp cost was eliminated, but, again, they are not useless. Unless, of course, SE made a change to their effects sometime in the last few months that I missed, that is.

Monks, in particular, can still see a good drop in their Tp if they happen to have a need to use Arm of The Destroyer to cause an instant silence on all nearby casters. Dragoons, as well, can drop their Tp considerably if they do a full DoT rotation on a target in between their bursts. It's not as common in a smaller arena such as Feast, but a lot of pressure plays require larger Tp expenditures, which require Tp regens. It's unlikely that you'll need help with that, so Army's Paeon is almost never needed, but Invig and goad are still handy if you're in a bind.

As for Summon II/Titan ... I can agree with that one. I can't even imagine when you might need to pull out Titan, unless you have the sudden need for an Area Denial ... but even then, that would still require a faster means of switching pets. It's just too slow to be viable, no matter what the circumstance.

[Lanze]

Basically most of the AoE abilities
Steel Cyclone and Overpower
Ring of Thorns and Doomspike
Quick Nock and Rain of Death

[SuperZay]

Basically most of the AoE abilities
Steel Cyclone and Overpower
Ring of Thorns and Doomspike
Quick Nock and Rain of Death

Those are still useful in Seal Rock for guarding nods against 2+ players.

[Lanze]

if only seal rock was a thing anymore