Which secondary Ultimate for Templar tank?

Narvuntien

I play a full hybrid templar tank (S&B and Ice Staff) for vet dungeons and normal trials.
Obviously my main ultimate is Warhorn but I am not sure what to do with my other ulti slot. Previously I had to use the spears ultimate for the passive but they changed it and I am not sure what to do with that slot anymore.

Options:
Solar Prison (Major Maim)
Spell wall (Combo with Deep thoughts)
Undo (the morph with the defensive passive)
Remembrance (Teamwide heal)

Liofa

There is only 1 more option to add to what you already listed. Barrier for 10% Magicka Recovery passive. I would probably go with Temporal Guard though.

Tasear

Undo or Remembrance

You could pull off some fancy 3 dps runs and just be off healer for group and tank.

Narvuntien

I had a Vet DC2 run that was struggling, my dps were 200 cp or so, I slotted Remembrance and suddenly everything got a lot easier when I could just save my team whenever they got low.

I'll keep grinding to level up undo, I only just unlocked it as an option.

Barrier interesting, I'll go level that up as well so I have it as an option.

Hotdog_23

I generally run barrier myself unless the group runs into trouble and I think another Ultimate would help better.

mocap

Barrier 24/7
Horn mostly for vet trials, even ratings.

Ysbriel

Spell wall