If the card has in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.

If you cast a card "without paying its mana cost," you can't choose to cast it for any alternative costs, such as emerge costs. You can, however, pay additional costs. If the card has any mandatory additional costs, such as that of Incendiary Sabotage, you must pay those to cast the card.

The card cast with Aetherworks Marvel's second ability is cast from your library.

Aetherworks Marvel's first ability triggers whenever any permanent you control is put into a graveyard from the battlefield, including Aetherworks Marvel itself and other permanents put into a graveyard at the same time as it.

Tokens that are sacrificed or destroyed are put into their owner's graveyard before ceasing to exist. If you controlled the token, Aetherworks Marvel's first ability will trigger.

Some triggered abilities that state that you "may pay" a certain amount of 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.

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.

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

Some spells and abilities that give you 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 .

If an effect says you get one or more , you get that many energy counters. To pay one or more , 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.

If a spell or ability with one or more targets states that you "may pay" some amount of , and each permanent that it targets has become an illegal target, the spell or ability won't resolve. You can't pay any even if you want to.

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

is the energy symbol. It represents one energy counter.

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.)