User blog comment:ChaseKing/Thumper, The Jack Rabbit/@comment-26186030-20150522163003/@comment-4773210-20150523205532

I'm inclined to agree. At present, (if I count right) his ultimate thumps 3 times at level 1, 6 times at level 2, and 14 (!) times at level 3, meaning the total base damage of the ability would be 90 / 360 / 1260 (!!!).

I would keep the duration and time between thumps constant so that it scales less erratically. I would also reduce the range of the ult, since 1200 units is a huge AoE radius. Unless you mean that the AoE diameter is 1200, which would be a 600-unit radius, and is much more in-line with other abilities like it.