Protector of Sparks

If one or more loyalty counters would be removed from
a planeswalker you control, that many minus one are
removed instead.
If one or more loyalty counters would be added to a
planeswalker you control, that many plus one are
added instead.
{3}{w}{u}{b}{r}{g}: Until end of turn, you may cast planeswalker spells without paying their mana cost