As long as you have nine or more poison counters, Ghoulbark, Opioid Researcher is indestructible.
+1: Until end of turn, Forests you control tap for an additional
. Gain a poison counter.
-3: Until your next upkeep, prevent all damage that would be dealt to players and permanents. Gain a poison counter.
-7: You gain two poison counters and an emblem with "Creatures you control get +3/+3 and have Ward
."
See Fall in with the Wong Crowd. What kind of planeswalker would exist in a plane with a drug problem? Who is responsible for the drug problem? Ghoulbark's illness and search for cures might make him find (name-bland) poppy. An opiod painkiller would fit the bill for something Ghoulbark would use to ease his suffering as he searches for a cure.
. Gain a poison counter" instead.
The +1 was just something that felt right for Ghoulbark. I had envisioned this being a six-drop. If it would be better for gameplay, I'd be fine making that ability be "Lands tap for an additional
The -3 ability is supposed to give the idea of feeling invincible from the drugs.
The third ability originally wasn't going to have poison counters as I wanted it to just feel like a traditional ultimate ability. This is supposed to represent the beneficial properties of that type of drug when used correctly.
All this being said, I don't think Ghoulbark is malicious to the point of being a drug dealer or prescribing it to others. However, he'd likely tell people how the drug he created helped him, and then show them how to make it, not considering or paying attention to the consequences of its effect on others.