* 502.19a - Echo is a triggered ability. "Echo" means "At the beginning of your upkeep, if this permanent came under your control since the beginning of your last upkeep, sacrifice it unless you pay its mana cost." [CompRules 2003/07/01]
* 502.19.Ruling.1 - The Echo payment is required if you gained control of the creature by any means, such as putting it into play from the graveyard, taking control from another player, or having the card phase in. [D'Angelo 1999/05/01]
* 502.19.Ruling.2 - The Echo payment is only required if you control this card at the beginning of your upkeep. [D'Angelo 1999/05/01]
* 502.19.Ruling.3 - If you gain and lose control of the card several times before your upkeep, you still only pay the Echo cost once. [D'Angelo 1999/05/01]
* 502.19.Ruling.4 - Effects which modify the cost to play a spell, like the Emerald Medallion or Gloom, cannot be used to modify the Echo cost. These effects only apply to the announcing of spells, and do not apply to the mana cost that Echo sees. [D'Angelo 1998/11/25]
* 502.19.Ruling.5 - This ability is put on the stack at the beginning of upkeep. If the permanent leaves play before this ability resolves, you still have to resolve it. Of course, you can just decide not to pay and there will be nothing to sacrifice. But you can also choose to pay if you really want to. [D'Angelo 1999/05/01]
* 502.19.Ruling.6 - You decide on resolution of the upkeep triggered ability whether to pay for the Echo cost or not. [Barclay 1999/06/02]
* Note - Also see Rule 203 for information on Mana Cost.
* Note - Also see Rule G5.1, "Echo".