Hearthpwn

Against warlock this is a weaker card because by the time even with druid ramping you get to 9 mana they would have life taped at least twice. Still against agro this is a good card for turning a losing game into a winning game. Healing them for 10 is well worth the price if you are healing yourself for 20+. It is a late game card so without ramping it is not that useful as we all know zoo/agro can kill you before you can reach turn 7.

I find poison seeds work better with token druid decks. Poision seeds is more of a zerg card where it sets the game down to who has the most minions on the board.

As for mills well for one mill is still weak in Hearthstone. The Rouge can do it pretty good, the Druid only has one card that allows him to mill and the rest you have to depend on coldlight brewmaster plays. Sure it maxes your health so when the inevitable fatigue comes along but it also heals your opponent too. You would need something like Alexstrasia to knock them down to 15 health. That is assuming you did not have to use it on yourself. 

I saw someone play a deck with Molten Giants, so that might work

I can see this working in a control/ramp deck with huge late game minions

it is good card when you play Ramp druid vs Aggro and combo decks :)