So theoretically Alex has infinite energy to regenerate so long as he has material to work with? Okay then.
Mountain blasting you say? Even if it's not permanent, blasting everything until he's out of bio-mass to use should suffice... assuming Lord Foul's energy lasts. How long can Lord Foul keep it up before he sends himself into remission?
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My Little Phineas and Ferb: Summer is Magic!