i'd bet, its pretty unlikey that he has two spades in his hand...but he might have one, probably the ace, so you don't want to check and give him the next card and give him the chance to out draw you...i wouldn't think he has a two in his hand or 44, not after calling a 400 raise...maybe he has QA. i'd make a large bet, as the only hands that beat you now are AA, QQ, or two spades...if he had a really strong hand i doubt he would check on the turn, because after he checkraised on the flop its less likely that you'll bet, so he'd want to bet for value/stop you out drawing him...maybe he raised to get a free card. Or maybe thats what he wants you to think?

You might be beat, but i'd still think i as ahead at this point, i'd probably go all in...if he has QQ or the flush, you've still got a (small) sliver of hope, if he got 22, well thats life...

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I love him who is ashamed when the dice fall in his favour and who then asks: Am I then a cheat? for he wants to perish.