If you can sacrifice the 4k then go for it. But if you manage to pull him after sacrificing that bp it was all for nothing. I would at least wait to see if they add a feature that we have for downgrading mags and rune stones applied to summon runes before you take that risk. At least then if you decide to sell some of your runes at least you keep a good chunk of bp and stats.

KoH is just short for King of Hell