Cheapest priced copy (Tempest): $2.29 at Card Kingdom, near mint, their price list as of .
Maddening Imp 
Creature — Imp · 1/1 · Rare · Tempest · #143
Flying
{T}: Non-Wall creatures the active player controls attack this turn if able. At the beginning of the next end step, destroy each of those creatures that didn't attack this turn. Activate only during an opponent's turn and only before combat.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
1 printing · $2.29 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Tempest | 143 | Rare | $2.29 | — |
One ruling from Wizards of the Coast
- 4 October 2004If a creature can’t attack because of some restriction, or because it is tapped, it is destroyed at the end of the turn.