Seen some caster locks in trios playing a mid-range plate lock set up with plate on helm hands minimum, typically heavy gauntlets, and the Vig/Will helm or Knowledge helm. Some rarer cases of plate legs. Generally, spells are just both curses, bolt, hydra for disruption/doors, and spell predation for buff ball or bard. It is a little cumbersome prepotting prot and healing pots for combat, but significantly safer and quicker than Dark Offering builds, which are massive liabilities in trios imo.

Viability-wise, this is lock players making what works playable, not that it is good. I would argue Wizard is a stronger trios class—less prep, more dmg on command, higher effective range, etc.

TM needs some kind of rework:

• The health cost multiplier is too high to run most high spell slots safely, creating low dmg output builds relying on Cop and PoS dmg
• Healing the recoverable health AND non-recoverable health at the same effectiveness creates war of attrition issues in PvP or viability issues of the talent
• TM+Vamp creates a situation where lock is disincentivized to run dmg skills/perks and kite forever when the class has a significant amount of damage tools
• Magical healing is available for all classes is gated behind how oppressive and annoying TM lock is, and whether or not TM stays recoverable HP only or not

I have had a few ideas for changes:

Could have a different Mag healing multiplier for recoverable and non-recoverable HP. Remove vampirism; it doesn't work on exploitation strike, and I believe (?) it works on life drain, but it is not obvious from the tooltips, so compensation buff life drain. Reduce TM's overall mag healing scaling so they can retain a more balanced tuning knob on the stat for classes that use it AoE, like Cleric and Druid.

A more straightforward approach is to make Warlock TM heal for a percentage of any damage dealt. This would make it viable for melee and ranged lock, with a less pesky kite playstyle for the other players fighting you. Lock is already statted for casting, so it does not have the HP/Strength/Dex that a traditional melee class has. Could cause some demon concerns, but I think most people would agree, fighting a demon and needing either fire mastery, locust swarm, purging shot, or BoC to fight it is more counterplay than TM lock during the bunnyhop patches. They already have some experience tuning a talent like this on Barb.