Historical Rules · 23 April 2010
Rule 113.8b
Official source text from the 23 April 2010 Rules release
An object that looks for a "[spell or ability] with a single target" checks the number of times any objects, players, or zones became the target of that spell or ability when it was put on the stack, not the number of its targets that are currently legal. If the same object, player, or zone became a target more than once, each of those instances is counted separately.