Cheapest priced copy (Commander 2020): $0.49 at Card Kingdom, near mint, their price list as of .
Thraben Doomsayer 
Creature — Human Cleric · 2/2 · Rare · Dark Ascension · #25
{T}: Create a 1/1 white Human creature token.
Fateful hour — As long as you have 5 or less life, other creatures you control get +2/+2.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
2 printings · $0.49 to $1.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander 2020 | 104 | Rare | $0.49 | — |
| Dark Ascension | 25 | Rare | $0.59 | $1.49 |
2 rulings from Wizards of the Coast
- 22 January 2011A creature whose toughness is being increased by Thraben Doomsayer's fateful hour ability loses that bonus as soon as its controller has 6 or more life (or as soon as Thraben Doomsayer leaves the battlefield). If damage marked on that creature is greater than or equal to its toughness after the fateful hour ability stops applying, the creature is destroyed and put into its owner's graveyard.
- 22 January 2011If Thraben Doomsayer's activated ability resolves while you have 5 or less life, the creature token will be 3/3 as it enters.