Cheapest priced copy (Tarkir: Dragonstorm Commander Tokens): $0.39 at Card Kingdom, near mint, their price list as of .
Timeless Witness 
Creature — Human Shaman · 2/1 · Uncommon · Modern Horizons 2 · #179
When this creature enters, return target card from your graveyard to your hand.
Eternalize {5}{G}{G} ({5}{G}{G}, Exile this card from your graveyard: Create a token that's a copy of it, except it's a 4/4 black Zombie Human Shaman with no mana cost. Eternalize only as a sorcery.)
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
5 printings · $0.39 to $2.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Modern Horizons 2 | 179 | Uncommon | $0.79 | $1.49 |
| Modern Horizons 2 | 358 | Uncommon | $0.79 | $1.99 |
| Tarkir: Dragonstorm Commander | 274 | Uncommon | $0.99 | — |
| Modern Horizons 2 Tokens | 5 | Common | $0.59 | $2.99 |
| Tarkir: Dragonstorm Commander Tokens | 11 | Common | $0.39 | $0.39 |
4 rulings from Wizards of the Coast
- 18 June 2021The token is a Zombie in addition to its other types and is black instead of its other colors. Its base power and toughness are 4/4. It has no mana cost, and thus its mana value is 0. These are copiable values of the token that other effects may copy.
- 18 June 2021If a creature card with eternalize is put into your graveyard during your main phase, you'll have priority immediately afterward. You can activate its eternalize ability before any player can try to exile it.
- 18 June 2021Once you've activated an eternalize ability, the card is immediately exiled. Opponents can't try to stop the ability by exiling the card.
- 18 June 2021The token copies exactly what was printed on the original card and nothing else, except the characteristics specifically modified by eternalize. It doesn't copy any information about the object the card was before it was put into your graveyard.