[elindauer]

I'm having a very hard time putting the donk-bettor on a hand we can beat. He can't possibly be bluffing the turn into all these players after all this action, and if he had a draw and was prone to bet for value, he'd probably have done it on the flop when he had the golden 3-bet the field opportunity.

This bet looks like somebody who has a pretty good hand, but who is concerned about the draws out against him. He wants to wait until the turn to see if the heart Q or J hits. When the blank 4d arrives, he thinks he's good and attacks. Is this KQ? Seems unlikely.

The best case for us is, I believe 9T where we actually have some outs. I think his most likely holding is KT. 99 and TT are possible but I think he'd just attack the flop with a holding that strong and all those players.

I don't think you are going to fold much that you want to fold with a raise. Any flush draw and any pair+straight draw is going to call. So, although your hand is vulnerable and you'd normally want to raise here, I think with this board and this action, calling is best. Tough call though.

good luck.
eric