Discussing Cavern of Souls
Perhaps you’ve heard conversation lately about a ruling involving Cavern of Souls. Why don’t I start with the current ruling and what you need to know, and then I’ll step back and talk about some of the thinking behind these actions.
Current Ruling: If you control Cavern of Souls, and you cast a creature spell of the chosen type, the presumption is that you activated the second ability. The spell can’t be countered. As the controller of Cavern of Souls, it is your responsibility to make sure the card is clearly visible (no stacking under other lands, your elbows, etc.). You don’t have to expressly say anything when casting the creature spell, but your opponent has the right to ask you to clarify your actions at any time. If you control more than one Cavern of Souls, it is your responsibility to make sure it is clear what creature types you have named for each of them. If, for whatever reason, you want to activate Cavern of Soul’s first ability and leave your creature spell vulnerable to counter Magic, you must explicitly say this as you cast the spell. If you’re going to an event in the near future and you have further questions, please make sure to ask the judge staff at that event.
Before this latest ruling, after a few controversial situations at recent marquee events, we announced a policy that said that tapping Cavern of Souls without expressly communicating your intent to activate the second ability meant you had actually activated the first ability, unless the game required you to use Cavern’s colored mana to cast the spell, in which case it was deemed unambiguous and the spell couldn’t be countered.