"You may cast this card only if a legendary creature you control would become the target of a spell or ability an opponent controls.

Regenerate target legendary creature. It gains hexproof until end of turn.

Draw six cards and lose 2 life."

This looks way too strong. An uncountable protection spell for 3 is already good, but then it also draws 6 cards? Even with its restrictions, it's busted in half. I'd say make it cost 4 mana at minimum. Maybe make it cost 5. Or just reduce the draw. A couple thing could be done to balance this.

This specifically targets a creature you don't control, implying that you (or someone else) are about to kill something, but then you decide to let them live for your own gain. I definitely need to tweak the amount of cards gained through playtesting, but that's what I wanted the card to do.