https://medal.tv/clips/56494181/d1337BE25oqn
The ult damage is 250 at level 3 + 40 per tick of the tremor (250+ (40*3) = 370).
His Q damage is 220. 220 + 370 = 590, which is the damage I dealt to the targets.
The only thing that can change the damage Rammus is dealing is the distance he is jumping in his ult, which increases the damage of the ult.