Cheapest priced copy (Conspiracy): $0.35 at Card Kingdom, near mint, their price list as of .
Marchesa's Infiltrator 
Creature — Human Rogue · 1/1 · Uncommon · Conspiracy · #22
Dethrone (Whenever this creature attacks the player with the most life or tied for most life, put a +1/+1 counter on it.)
Whenever this creature deals combat damage to a player, draw a card.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
1 printing · $0.35 to $0.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Conspiracy | 22 | Uncommon | $0.35 | $0.79 |
4 rulings from Wizards of the Coast
- 29 May 2014Once dethrone triggers, it doesn't matter what happens to the players' life totals before the ability resolves. You'll put a +1/+1 counter on the creature even if the defending player doesn't have the most life as the ability resolves.
- 29 May 2014In a Two-Headed Giant game, dethrone will trigger if the creature attacks either player on the team with the most life or tied for the most life.
- 29 May 2014The +1/+1 counter is put on the creature before blockers are declared.
- 28 July 2023Dethrone doesn't trigger if the creature attacks a planeswalker, even if its controller has the most life. The same is true if the creature attacks a battle, even if its protector has the most life.