Since Colossus Slayer is triggered from a successful attack, you could put the link in the damage type of the weapon. So Colossus would be save as an Ability macro, for example called colossus on a player character called bob : &{template:simple} {{rname=Colossus Slayer}} {{mod=1d8}} {{normal=1}} {{r1=[[1d8]]}} then change the DAMAGE TYPE field on bob's weapon attack to: [Piercing](~bob|colossus) Obviously swapping the word Piercing for the correct damage type for the weapon. You can then click the damage type to roll Colossus damage:
