Cheapest priced copy (Ravnica Allegiance): $0.59 at Card Kingdom, near mint, their price list as of .
Cavalcade of Calamity 
Enchantment · Uncommon · Ravnica Allegiance · #95
Whenever a creature you control with power 1 or less attacks, this enchantment deals 1 damage to the player or planeswalker that creature is attacking.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.59 to $2.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Ravnica Allegiance | 95 | Uncommon | $0.59 | $2.49 |
3 rulings from Wizards of the Coast
- 25 January 2019A creature with power 0 or less can attack, as long as no rule or effect prohibits it from doing so. Many creatures with 0 power have defender, but not all do.
- 25 January 2019If multiple creatures you control with power 1 or less attack, Cavalcade of Calamity’s ability will trigger for each of those creatures. Each ability will cause Cavalcade of Calamity to deal 1 damage to the appropriate player or planeswalker.
- 25 January 2019The power of the attacking creature is checked only when the ability triggers. Once it triggers, Cavalcade of Calamity will deal 1 damage to the appropriate player or planeswalker even if the creature’s power changes or the creature leaves the battlefield before the ability resolves.