IT also damages friendly units even if you remove the targets allowed 'friend'..
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Anyway, thank for the replies. It seems that it is no possbile except for triggering annd I don't like that so I will make the unit do something else.
Well, you have to - friend, - air, - invulnerable, - self, + Enemy.
I think u missed - self. Nvm, it works.
But now you will have another problems:
1. Immolation doesn't give effect normally. It will in my solution.
2. Disease cloud gives effect for specified time. Disease source doesn't has to be in range. Here disease works only when unit is in range.
3. Units are not feeling attacked. They stay like "nothing happening". They are not detecting this like negative effect, which hurts them so they don't escape like they should normally.
EDIT:
4. U don't get experience when unit is lasthited by effect of this ability.
5. Originally Disease Cloud wouldn't kill unit. (leaves it on 2 hp). Here it will.
If you want to get the interesting effect use: Life Regeneration Aura. It will only give a unit effect when it's hp less than max. You can call it infection. You know, unit has to be hurt to get the infection effect, which hurts it more.