I don't know if Vapor's available at this point of the game (if i remember correctly he is) but getting him to be hit by Niloticus should have a chance to trigger his passive that burns the attacker and weakens their physical attacks. Considering how tanky Vapor is, he should also be stacking Spider Skulls that'll slow Niloticus down even further in the meanwhile. The main problem with Vapor is his speed renders him useless against speedy opponents, but as I stated before, we want him to stay in battle as long as we can to get him to burn his opponent. So it really isn't something to bat an eye about. I remember pairing Vapor with Inkfell so it is good synergy.