Basic healing spell Carl reserves just enough mana for after dumping the rest into Günter.
Carl put most of his mana into Run, Little Günter, Run but deliberately left enough for a single application of the Healing spell. Blind and sensationless after the Waffle Maker blast, unable to see or hear but still able to think and access his inventory, he clicked a Fine Healing Potion and cast Healing on himself.
He regretted it almost immediately: the combination reassembled his flattened body, and feeling every nerve and pulverized bone come back online at once hurt more, he says, than anything ever should.
The last mana Carl saves, and the reason he is conscious for his own reconstruction.