Cheapest priced copy (Ikoria: Lair of Behemoths): $1.99 at Card Kingdom, near mint, their price list as of .
Bio-Quartz Spacegodzilla 
Brokkos, Apex of Forever
Legendary Creature — Nightmare Beast Elemental · 6/6 · Mythic · Ikoria: Lair of Behemoths · #378
Mutate {2}{U/B}{G}{G} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)
Trample
You may cast this card from your graveyard using its mutate ability.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
5 printings · $1.99 to $37.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Ikoria: Lair of Behemoths | 179 | Mythic | $1.99 | $3.49 |
| Ikoria: Lair of Behemoths | 299 | Mythic | $3.49 | $14.99 |
| Ikoria: Lair of Behemoths (Bio-Quartz Spacegodzilla) | 378 | Mythic | $37.99 | $34.99 |
| Ikoria: Lair of Behemoths Promos | 179p | Mythic | $7.49 | $5.99 |
| Ikoria: Lair of Behemoths Promos | 179s | Mythic | — | $2.99 |
3 rulings from Wizards of the Coast
- 17 April 2020If you cast Brokkos with the permission granted by its last ability, you must pay its mutate cost to cast it. You can't choose to pay its mana cost or another alternative cost.
- 17 April 2020If another effect gives you permission to cast Brokkos from your graveyard, you may cast it for any cost associated with that permission.
- 17 April 2020Casting Brokkos with the permission granted by its last ability doesn't change when you can cast it.