Cheapest priced copy (Commander Legends: Battle for Baldur's Gate): $1.79 at Card Kingdom, near mint, their price list as of .
Mirror Entity 
Creature — Shapeshifter · 1/1 · Rare · Lorwyn · #31
Changeling (This card is every creature type.)
{X}: Until end of turn, creatures you control have base power and toughness X/X and gain all creature types.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
14 printings · $1.79 to $49.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander 2013 | 17 | Rare | $2.49 | — |
| Commander 2016 | 70 | Rare | $2.29 | — |
| Commander Legends: Battle for Baldur's Gate | 701 | Rare | $1.79 | — |
| Commander Anthology | 16 | Rare | $1.99 | — |
| Lorwyn | 31 | Rare | $2.99 | $49.99 |
| Murders at Karlov Manor Commander | 75 | Rare | $1.79 | — |
| Modern Masters 2015 | 26 | Rare | $2.29 | $8.99 |
| Outlaws of Thunder Junction Commander | 83 | Rare | $2.29 | — |
| The List | CMA-16 | Rare | $1.99 | — |
| The List | LRW-31 | Rare | $1.79 | — |
| The List | OTC-83 | Rare | $1.79 | — |
| Secret Lair Drop | 2514 | Rare | $3.99 | $7.49 |
| Time Spiral Remastered | 297 | Special | $2.79 | $29.99 |
| Crimson Vow Commander | 94 | Rare | $1.99 | — |
3 rulings from Wizards of the Coast
- 19 March 2021Changeling applies in all zones, not just the battlefield.
- 19 March 2021Mirror Entity's ability overwrites any effects that previously set a creature's base power and/or toughness. Any existing effects or counters that raise or lower a creature's power and/or toughness continue to apply to the creature's newly-set power and toughness.
- 19 March 2021Activating the ability with X = 0 will cause all creatures you control to become 0/0 and be put into the graveyard.