Unstable Loyalty

Enchant Planeswalker
Enchanted Planeswalker's controller may activate abilities of enchanted Planeswalker even if it would cause enchanted Planeswalker to have negative loyalty.
If enchanted Planeswalker has no loyalty counters and more loyalty counters have to be removed from it, exile it, then put it under a different player's control with the number of loyalty counters that should be removed. Then enchant Unstable Loyalty to it.