Historical Rules · 1 October 2010
Rule 704.5i
Official source text from the 1 October 2010 Rules release
If a planeswalker has loyalty 0, it's put into its owner's graveyard.
Historical Rules · 1 October 2010
Official source text from the 1 October 2010 Rules release
If a planeswalker has loyalty 0, it's put into its owner's graveyard.