First thing is, don’t pot Wilbur until you run out of non-stacked-color stuns. That will save on the pots.
Second thing is, even when Wilbur is up, if almost everyone on your side has 4*-flimsy defenses, you’re going to absorb a lot of damage from the big titans. That will likely push Tarlak to the point where, when Wilbur’s buff goes down, he gets one-shotted. So you probably need a decent healer too.
Also, when the titan uses its special, everyone will take a bunch of damage. And the flimsiest defenses will distribute their extra damage to everyone else. So Tarlak really works best with reasonably sturdy heroes around him. His defense already sucks, so he’s sharing a lot of damage with everyone else. If he receives a lot of damage from others too…ouch.
Only pot Tarlak when you have a 3-match lined up on the weak spot or several matches/a cascade of your color seems reasonably likely. That will save on pots over the long run.