Aethergeode Miner

Some spells and abilities that give you {E} may require targets. If each target chosen is an illegal target as that spell or ability tries to resolve, it won't resolve. You won't get any {E}.

Energy counters are a kind of counter that a player may have. They're not associated with any specific permanents.

Energy counters aren't mana. They don't go away as steps, phases, and turns end, and effects that add mana "of any type" can't give you energy counters.

Keep track of how many energy counters each player has. Potential ways to track this include writing theme down on paper or using dice, but any method that is clear and mutually agreeable is fine. (At higher levels of tournament play, dice may not be allowed for tracking counters that players have.)

Some triggered abilities state that you "may pay" a certain amount of {E}. You can't pay that amount multiple times to multiply the effect. You simply choose whether or not to pay that amount of {E} as the ability resolves.

After Aethergeode Miner returns to the battlefield, it will be a new object with no connection to the creature that was exiled. It won't be in combat or have any additional abilities it may have had when it was exiled. Any +1/+1 counters on it or Auras attached to it are removed, and any Equipment will no longer be attached.