I was actually planning on making this before Saviours :(.
Anyway:
Channeling X (When you play this spell, remove it from the game face up with X channeling counters on it instead. At the beginning of your upkeep, remove a channeling counter from this and put a copy of it on the stack. Then, if there are no counters on this, put it into its owner's graveyard.)
Looks okay?
Example:
Variant Wrath 2WWW
Sorcery
Channeling 7 (When you play this spell, remove it from the game face up with 7 channeling counters on it instead. At the beginning of your upkeep, remove a channeling counter from this and put a copy of it on the stack. Then, if there are no counters on this, put it into its owner's graveyard.)
Destroy each creature with converted mana cost X or less, where X is the number of counters on ~.
Anyway:
Channeling X (When you play this spell, remove it from the game face up with X channeling counters on it instead. At the beginning of your upkeep, remove a channeling counter from this and put a copy of it on the stack. Then, if there are no counters on this, put it into its owner's graveyard.)
Looks okay?
Example:
Variant Wrath 2WWW
Sorcery
Channeling 7 (When you play this spell, remove it from the game face up with 7 channeling counters on it instead. At the beginning of your upkeep, remove a channeling counter from this and put a copy of it on the stack. Then, if there are no counters on this, put it into its owner's graveyard.)
Destroy each creature with converted mana cost X or less, where X is the number of counters on ~.
Bored? Watch this.