Care to explain why and with what skill order, masteries, runes, and item build?
In spider form her and her spiderlings pretty much instantly kill any ghouls he could put out negating their existence. Switch to human poke with Q, if you see him drop a ghoul, spider form and Q onto it so your spiders eat it. This pretty much removes his sustain. Just keep on poking and taking care of his ghouls gradually, he'll go oom long before you because your spider skills take no mana. When he gets to about half health you can jump on him and kill him with ignite up sometimes without. Buy a chain vest after your haunting guise and it's like he isn't even there.
and no rihoof that's a terrible plan --- Elise is my waifu! Hands off!