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.)
Energy counters are a kind of counter that a player may have. They're not associated with any specific permanents.
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}.
Last observed on Scryfall 2 months ago at $0.29. Over the trailing 90 days the price moved between $0.02 and $0.33 across 50 observations. Cross-checked across TCGplayer, eBay sold, Cardmarket EU, and Star City.
This printing is one of 3 catalogued treatments from KLD — the lineup includes Foil and Nonfoil alongside the standard finish. Across our catalog the Rarix library tracks every variant in the same family so collectors can compare price, scarcity and demand inside a single lineage.
Card #3 of *Kaladesh*, the set that shipped alongside the September 2016 Kaladesh release.
Card type: Creature — Bird, color identity white, printed at rare. Rares occupy the bottom-of-pack rare slot in standard boosters. Mana cost: {2}{W}{W} (4 converted). Keyword abilities: Flying.
Legal across the major constructed formats — Modern, Legacy, Vintage, and Commander — plus Standard rotation play.
EDHrec ranks this card #7,346 in Commander, putting it in the niche-pick tier of the format's playable pool.
Illustrated by Scott Murphy. Rarix catalogs 392 other cards credited to this artist.
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. Scott Murphy
Card data via Scryfall. Rarix is fan-made; not endorsed by the rights holders.
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.
{E} is the energy symbol. It represents one energy counter.
If a spell or ability with one or more targets states that you "may pay" some amount of {E}, and each permanent that it targets has become an illegal target, the spell or ability won't resolve. You can't pay any {E} even if you want to.
If an effect says you get one or more {E}, you get that many energy counters. To pay one or more {E}, you lose that many energy counters. You can't pay more energy counters than you have. Any effects that interact with counters a player gets, has, or loses can interact with energy counters.
Some triggered abilities that state that you "may pay" a certain amount of {E} describe an effect that happens "If you do." In that case, no player may take actions to try to stop the ability's effect after you make your choice. If the payment is followed by the phrase "When you do," then you'll choose any targets for that reflexive triggered ability and put it on the stack before players can take actions.
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.
Aetherstorm Roc's second triggered ability resolves before blockers are chosen. A creature tapped this way won't be able to block.
You don't have to target a creature with Aetherstorm Roc's last ability. If you do choose a target, and that target becomes illegal, the ability doesn't resolve and you won't be able to pay {E}{E} to put a counter on Aetherstorm Roc.
A creature entering the battlefield at the same time as Aetherstorm Roc causes its first triggered ability to trigger.
