How do I increase maximum life of a unit permanently?

I tried to add the manual of health ability to a unit and make the unit use that ability but it doesn't get added. For some reason I can't add item abilities with no target to a unit if it normally is meant for a hero to use.

I don't think that upgrades will work because I want to increase the life of revived units using either ressurection or animate dead but don't want the non-revived versions of them having the same upgrade.

I also want to increase the life by a certain percentage, not a specific amount. There is no sbility that does that or not that I know of.

Anyone know how?

Well, I think you have two options here:

1) Turn the unit into a hero and then use the manual of health. However, you wanted to increase by a percentage, so I dont think this would work.

2) Make another unit copied from te first unit with the exact same stats except the HP upgrade and just replace units when you need to. That would work as long as it isnt a variable increase.

You can use weaaddar's bonus mod http://www.wc3campaigns.com/showthread.php?t=47554