what does Target Lock do on toons exactly?

Warning to those that would otherwise try it:

The combo of zIG88, zProbot, and zTalzin does NOT work in practice. It fails due to IG88. His 3 health and 7 protection, and 2 potency, means that a care bear can kill him, he can't land target lock, and so he is a waste of space.

In a full BH squad he might be useful, but in squads made up of Boba, Talzin, IG88, Probot, Wampa, Zombie, GK, etc... well I cant get it to work at all. My last match was versus a Palp lead, and I pressed the screen a grand total of 0 times. Got no turns at all.

^ It's a good thought, but I tried it. Problem is Han and/or CLS. Both can one-shot IG88. CLS ignores the taunt, while Raid Han can't be evaded.
Gives you more of a chance vs. Palp if Target Lock sticks so that Sion/whoever can't taunt, though, you are right

Yeah. Just have to put him on a team where someone else is more dangerous and will get primaried. Thrawn or Nihilus fit with any team and will draw and can survive a CLS or Han open.