By 600% multiplier, you mean deals 600% chance of 130 at a random chance?
E- unit starts effect of ability
C- ability being cast == your ability
A-set dmg = 130
If- random integer between 1 and 100 <= 25 (this is % chance to use multiplier)
Then- set dmg = dmg + (dmg * 6)
damage (target of ability being cast) by (dmg) of type pure
Trigger:
- UnitDamageTarget (Artimetic (100+30)*600)