Blitzcrank 2XKO combo: 774 damage, expert+. Start with j.{2H} > H for max damage (948 with double down SS2+SS2, 1026 SS2 + SS3)
M > 2M(1) > H > S2 > 4T > H > S2|T > 9dl.j.H > 6H > H > 2H > j.9H > j.S1 > dl.j.H > H > 6H > 2S1 > 666H|2T > j.H > 2j.H > dl.j.S1 > S1 + L
Start with j.{2H} > H for max damage (948 with double down SS2+SS2, 1026 SS2 + SS3)