You may play that card for as long as it remains exiled, and mana of any type can be spent to cast that spell.
The Pocket version offers a friendly, hand-holding tutorial for those unexperienced with the rules, guiding you through the various aspects of each battle gently
The cards exclusivity is a key factor driving its price, as only a select number were made available to tournament participants
On the bright side, Hyper Flame only does nothing if the player has no energy to discard, so it can still deal damage if they're adequately prepared
However, Mindslaver's salt factor comes from the fact that in commander, there are numerous ways for players to consistently return artifacts from their graveyard to the battlefield
Its single-player, sure, but the strategic overlap with Magic is huge