Cheapest priced copy (Streets of New Capenna): $0.49 at Card Kingdom, near mint, their price list as of .
Undercover Operative 
Creature — Shapeshifter Rogue · 0/0 · Rare · Streets of New Capenna · #63
You may have this creature enter as a copy of any creature on the battlefield, except it enters with a shield counter on it if you control that creature. (If it would be dealt damage or destroyed, remove a shield counter from it instead.)
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $0.49 to $2.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Streets of New Capenna Promos | 63p | Rare | $2.49 | $2.49 |
| Streets of New Capenna Promos | 63s | Rare | — | $2.29 |
| Streets of New Capenna | 63 | Rare | $0.59 | $0.79 |
| Streets of New Capenna | 414 | Rare | $0.49 | $1.49 |
6 rulings from Wizards of the Coast
- 29 April 2022Shield counters don't prevent players from sacrificing creatures.
- 29 April 2022Removing a shield counter in this way isn't the same as regenerating a creature.
- 29 April 2022A creature with a shield counter on it may still be destroyed by state-based actions if it has damage marked on it equal to its toughness or has been dealt unpreventable damage by a source with deathtouch.
- 29 April 2022“Shield” is not an ability that creatures have and shield counters are not keyword counters. If a creature with a shield counter loses its abilities, the shield counter will still protect it as normal.
- 29 April 2022If a permanent that would be dealt damage has more than one shield counter on it, that damage is prevented and only one shield counter is removed.
- 29 April 2022If a permanent with a shield counter is dealt unpreventable damage, that damage will be dealt and a shield counter will still be removed.