Cheapest priced copy (Core Set 2020): $2.49 at Card Kingdom, near mint, their price list as of .
Knight of the Ebon Legion 
Creature — Vampire Knight · 1/2 · Rare · Core Set 2020 · #105
{2}{B}: This creature gets +3/+3 and gains deathtouch until end of turn.
At the beginning of your end step, if a player lost 4 or more life this turn, put a +1/+1 counter on this creature. (Damage causes loss of life.)
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
3 printings · $2.49 to $12.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Core Set 2020 | 105 | Rare | $2.49 | $11.99 |
| Core Set 2020 Promos | 105p | Rare | $3.49 | $12.99 |
| Core Set 2020 Promos | 105s | Rare | — | $9.99 |
4 rulings from Wizards of the Coast
- 12 July 2019It doesn't matter whether a player has 4 or less life than they started the turn with. If a player lost 4 life but also gained 6 life, that player still lost 4 life.
- 12 July 2019Knight of the Ebon Legion looks at your entire turn to determine whether a player lost 4 or more life. It doesn't matter how many players lost 4 or more life, only whether anyone did. It also doesn't matter whether Knight of the Ebon Legion was on the battlefield when they lost life.
- 12 July 2019A player loses life if they pay life.
- 12 July 2019A player doesn't need to have lost 4 life all at once. If a player loses 2 life twice during a turn, that player lost 4 life during that turn, and Knight of the Ebon Legion receives a +1/+1 counter.