A permanent card is an artifact, creature, enchantment, land, or planeswalker card.

The mana value of a card in your graveyard is determined solely by the mana symbols printed in its upper right corner. The mana value is the total amount of mana in that cost, regardless of color. For example, a card with mana cost {1}{U}{U} has mana value 3.

If a card in your graveyard has no mana symbols in its upper right corner (because it's a land card, for example), its mana value is 0.

If the mana cost of a card in your graveyard includes {X}, X is considered to be 0.

You can target any permanent card in your graveyard with mana value 2 or less, not just one that was put there from the battlefield this turn.

Revolt abilities check only whether a permanent you controlled left the battlefield this turn or not. They don't apply multiple times if more than one permanent you controlled left the battlefield. They don't check whether the permanent that left the battlefield is still in the zone it moved to.

Revolt abilities don't care why the permanent left the battlefield, who caused it to move, or where it moved to. They're equally satisfied by an artifact you sacrificed to pay a cost, a creature you controlled that was destroyed by Murder, or an enchantment you returned to your hand with Leave in the Dust.

Tokens that leave the battlefield will satisfy a revolt ability.

Energy counters aren't permanents. Paying {E} won't satisfy a revolt ability.

All cards in the Aether Revolt set with triggered revolt abilities use an intervening "if" clause. A permanent you controlled must have left the battlefield earlier in the turn in order for these abilities to trigger; otherwise they do nothing. In other words, there's no way to have the ability trigger if no permanent you controlled has left the battlefield that turn, even if you intend to have one do so in response to the triggered ability.