Well, not directly...
You will need to use abilities to achieve this, but there are vJass systems out there, which will do this for you, like Status, by Jesus4Lyf, which is used like this (Attack is used in this example ):
Trigger:
- Custom script: call Status[ GetTriggerUnit() ].modDamageBonus( 100 )
This will give 100 extra damage to (Triggering unit)
EDIT: komaqtion already do it :x anyway..
PS koma, you forget the include bonus
Oh, the syntax of [ljass]GetHeroInt()[/ljass] ? XD
Yeah, then use this instead:
Trigger:
- Custom script: call Status[ GetTriggerUnit() ].modDamageBonus( 500 + GetHeroInt( GetTriggerUnit(), true ) * 10 )