If The Snapstone Wielder is your
commanderA designated card for a Commander deck, governed by the command-zone, color-identity, and Commander rules. (CR 903) and your deck contains no land cards, your starting hand size is four and for the rest of the game, at the beginning of your upkeep, you get a mana
counterTo counter a spell or ability is to cancel it: remove it from the stack without resolving it. A counter on an object or player is instead a marker that changes characteristics or interacts with rules or abilities; for example, a +1/+1 counter modifies a creature’s power and toughness. (CR 701.6; 122.1). During each of your turns, you can spend mana of any color equal to the number of mana
countersTo counter a spell or ability is to cancel it: remove it from the stack without resolving it. A counter on an object or player is instead a marker that changes characteristics or interacts with rules or abilities; for example, a +1/+1 counter modifies a creature’s power and toughness. (CR 701.6; 122.1) you have. (You want mana on opponent's turns, you're on your own. Who needs instant-speed interaction?)
Whenever The Snapstone Wielder enters or attacks,
castTo cast a spell is to take it from the zone it’s in (usually the hand), put it on the stack, and pay its costs, so that it will eventually resolve and have its effect. A player may cast a spell if they have priority. See rule 601, “Casting Spells.”
To cast a card is to cast it as a spell. (CR 701.5) a random nonland Magic card without paying its mana cost. If it has targets, choose the targets at random.