[iggymcfly]

There's really only two hands that make sense here: 22xx and 456 with diamonds. If you check, you don't have to worry about a lower set betting, so I think you can check/fold pretty comfortably, and if you bet, 222 will almost certainly call one more bet.

The problem is that I think the wrap is much more likely than the lower set here. All in all, I think the best play is to check/fold here. The check behind flop/raise turn actually defines villain's hand really well here to the point that we're almost sure that if villain's drawing, he has 45 in his hand since his draw had to improve on the turn for him to wait for that street to raise. Thus, there's no reasonable hand villain can bluff with, and villain will very rarely value-bet worse than what we have.

Maybe if he bets 1/3 pot and you get suspicious he might have 88 or something, you can look him up, but I think most of the time, check/folding is the correct play here. (Note: This in no way means, you're giving up on the hand. Villain will check behind fairly often. It's just that when he bets, you're beat.)

Oh, BTW, if you do decide to lead, a smidge under half-pot is the right amount. You're not really repping a bluff at all given your line, you're just looking for a stubborn call from something like 222 that knows they're beat and wants to see your hand to make sure.