Problems with Roar item

I have a problem with a roar item. It's a potion that has active charges. The problems are that I cannot give it more than 10% damage increase (and I need it to), and the unit does not get these effects when under Spell Immunity.

Anyone know work-arounds for these?

Replies are greatly appreciated.

What do you mean it cannot give more than 10%? Just change the bonus damage value on the ability the item uses.

As for spell immunity, that's kind of the point, a spell immune unit is immune to spells.

You must make ability "hero" and set its level req to 2, then set back to item, this will allow spell override spell immunity.

Diod, you're saying the steps are:

1.) Make item ability
2.) Check Hero ability
3.) Make ability req: 2
4.) Make item ability

Results: It works?

btw, i was saying that it has a limit of "10" which is 1000%.