Modify Attack Damage of non-hero Units

[Templarion]

I am creating a spell which increases a non-hero unit's attack damage temporarily.

The increase of the damage must NOT be percentage but a number.

So, is it possible to either add "Number of Dies" or grant a "Custom Upgrade" for a while to increase unit's damage?

If possible, I would really like to do this through triggers.

 

[Persen]

Command Aura can be set to "Flat Bonus"
I think that would make it give a constant dmg bonus.

If you use this method it has to be triggered spell, though.