When I read it, the description implies to me that it will take 10% of your health every tick and best case scenario (with heals) it will allow 10 ticks maximum. Each tick will restore (2.5% of the caster's current health times the number of aa points invested) points of power.
When I tried it out just a moment ago, when it should have restored 3.1k power, it only restored about 600 power. You're right, it's seriously not doing even remotely close to what it should be doing. If it's consuming that much health, it had better restore a lot more power than 1/8th the amount of 1 mana flow.