If you wanna go 15+ kills almost every game heres how. Pantheon mid against AP squishhies and the camping Jungler and you get fed so much you may as well be at a buffet.

Pros
You annihilate everyone
You can dunk better than Lebron
You destroy all those little AP squishies early in mid

Cons
He makes you feel like a total badass and try going in 1 v 3
Super mana hungry early on

Get some AP early on so your super dunk and mini dunk does more damage but late game sell your AP items for more AD or tanky items. Late game your so fed that it doesnt matter if your stun does more damage and your skyfall already does 1k damage.

Try not to be like me and super dunk into 5 people and have no teammates there and get railed. Try to time your ult with your team to get in and destroy them all. Stunning their AD carry or AP carry can buy your team (and mainly you) enough time to drop them then drop everyone else.

I'm not the best with runes but try to get tank runes and a lot of AD and crit runes is what i would suggest.