Growing enchantment

Growing enchantments are enchantments that start out without the ability to do anything but "grow". A "growing" enchantment accumulates counters each turn, building up to grant the player a boon proportional to the number of counters.

Although other spells with a similar mechanic have appeared before or since, growing enchantments were a widespread theme in the Urza block.

Rulings

• In a sense, these enchantments behave like delayed-effect sorceries. You cast one, then you wait. The more turns you wait before sacrificing it to get its effect, the bigger that effect will be.
• Putting a counter on the enchantment when its upkeep trigger resolves is always optional.
• The sacrifice ability's effect checks the enchantment's last existence on the battlefield to see how many counters were on it.
• There are also two artifacts in the set that behave this way: Barrin's Codex, which accumulates page counters, and Lotus Blossom, which accumulates petal counters. Powder Keg was released in the next set with a destructive effect.
• Thirteen years later, Golden Urn and the Shrine cycle from New Phyrexia follow the same theme, though the Shrines have the bonus ability to gain counters when a spell of an appropriate color is cast.

From Urza's Saga

• Discordant Dirge
• Lilting Refrain
• Midsummer Revel
• Recantation
• Rumbling Crescendo
• Serra's Hymn
• Serra's Liturgy
• Torch Song
• Vile Requiem
• War Dance

From Urza's Destiny

• Archery Training
• Festering Wound
• Incendiary
• Momentum
• Private Research