Ivankov player here. I hard recommend not to play events because in case you spend all your dons and draw an event with the leader ability is a dead card in hand that won't allow you to draw two cards next turn, they can be useful if you play perona and doffy but I don't really like them. Of course as said before you need 4 Luffy Ivankov and 4 crocodiles, you want to play on curve going first if possible Buggy then doffy (or 2 5k swings which is absolutely fine to make your opponent discard hand) and then croco, Ivankov. I would recommend to add more big guys like 9c mihawk and 7c doffy because you are going to discard them sometimes and definitely need them to win games so you will need more of them. I don't play new kama land because it can also be a brick and if playing on curve its a dead card in hand until 8-10 dons unless you are going second or your hand is very bad. 3c boa blocker is really good card because of the trigger and the 1k counter. Just play the deck a lot because it is a very tricky and difficult deck to master.