dont sell your runes, its not worth it, you will pull him eventualy if you just keep playing the game, also new summons will be released that can be substituted for him and later even replace him entirely. china has a summon that reduces enemy resistance by 20% per chase hits 3 people and it stacks 5x, so u reduce ur enemies res to 0 which is way better than koh. plus if u buy him then pull him later you will regret all of the lost power

The fact that those summons cost above 10k hurts me. Gamariki seems like the only one I would be willing to buy since I believe she is the only summon that can decrease a stat (reduces resistance for those who don't know).