The Gatewatch

The Gatewatch can't be countered.
When a planeswalker dies, cast this card from your graveyard, deck or exile without paying its mana cost.
Search your library, graveyard, sideboard, exiled cards and all other cards you own for a Gideon, Jace, Liliana, Chandra, Nissa, Ajani and Teferi planeswalker and put them onto the battlefield. This card overrides the legendary rule.
Members sworn by oath to watch and protect.