Reverse Magic: When this creature is targeted by an incantation or enchantment spell controlled by an opponent, you must reveal Reverse Magic during the Counter Spell Step. You take control of that spell. Redirect it back to the caster, who now becomes the target of the spell. If the spell cannot target the caster, it is countered. Then, destroy reverse magic.
Say for example, the Warlock casts explode on the Beastmaster's regenration belt, and the Beastmaster has reverse magic. Can the Beastmaster change the target of the spell to the warlock's lash of hellfire, paying the 2 mana difference? (regeneration belt costs 6, lash of hellfire costs