(6/16/2023) The trigger event doesn't have to specifically refer to legendary permanents or to artifacts, nor does it have to specifically refer to when something "leaves the battlefield." For example, an ability that triggers "whenever a creature dies" would trigger twice if a legendary creature or an artifact creature dies while Gandalf the White is on the battlefield, as would an ability that triggers "whenever a permanent is put into a graveyard from the battlefield." (6/16/2023) Look at each legendary permanent and each artifact as it exists on the battlefield, taking into account continuous effects, to determine whether any triggered abilities will trigger multiple times
Where it gets rather out of hand is the back end
Return it to the battlefield under your control tapped and attacking at the beginning of the declare attackers step on your next turn, then return Meandered Towershell to the battlefield under its owner's control attached to that creature." As the creature returns to the battlefield because of the delayed triggered ability, its controller chooses which player, planeswalker, or battle it's attacking
Special Summon it in Defense Position, but its effects are negated, also banish it during the End Phase
