Historical Rules · 29 September 2017
Rule 719.5
Official source text from the 29 September 2017 Rules release
No player can be forced to perform an action that would end a loop other than actions called for by objects involved in the loop. Example: A player controls Seal of Cleansing, an enchantment that reads, “Sacrifice Seal of Cleansing: Destroy target artifact or enchantment.” A mandatory loop that involves an artifact begins. The player is not forced to sacrifice Seal of Cleansing to destroy the artifact and end the loop.