Volatile Rig loves attacking. It fact, it has an ability that says it has to attack each turn if able. But what if your opponent has a Sphere of Safety out? Does that mean I have to pay every turn to make it attack?
The answer is no. Sphere of Safety adds a cost to creatures that are declared as attackers towards them or a planeswalker they control. And the Rig only attacks if able: you’re not forced to generate the mana to pay for the extra cost to make it attack, so if you don’t want the Rig to attack, you don’t have to pay and it won’t attack (because it’s not able). So if you want to attack with the Rig, you can, assuming you can pay X. If you don’t or can’t pay X, then the Rig doesn’t have to attack (caveat for multi-player games, where it would still have to attack a different player if able). This could be handy if you want your Rig to be available as a blocker next turn or you’d rather leave your lands untapped so you can cast spells later on.
Today’s Rules Tip written by Nathan Long (Welcome to the team!)