donking the turn, if you are going to do it with on $4 seems terrible. The play looks so weird that AK/ maybe AQ might call a street (in which case $4 is not enough), and it will definitely fold out a ton of hands that might bet a street.

Now that we're on this turn, I guess c/c and then see what the river brings. He has 0 spade draws in his range so you are hoping for him to catch up/think his QQ/KK are good.

With his stats it seems crazy not to 4bet pre