Cheapest priced copy (The Lost Caverns of Ixalan): $1.99 at Card Kingdom, near mint, their price list as of .
The Mycotyrant 
Legendary Creature — Elder Fungus · */* · Mythic · The Lost Caverns of Ixalan · #305
Trample
The Mycotyrant's power and toughness are each equal to the number of creatures you control that are Fungi and/or Saprolings.
At the beginning of your end step, create X 1/1 black Fungus creature tokens with "This token can't block," where X is the number of times you descended this turn. (You descend each time a permanent card is put into your graveyard from anywhere.)
Legal inCommanderBrawlStandardPioneerModernLegacyVintage
Not legal inPauper
4 printings · $1.99 to $4.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| The Lost Caverns of Ixalan | 235 | Mythic | $1.99 | $2.49 |
| The Lost Caverns of Ixalan | 305 | Mythic | $3.49 | $4.49 |
| The Lost Caverns of Ixalan Promos | 235p | Mythic | $2.99 | $2.99 |
| The Lost Caverns of Ixalan Promos | 235s | Mythic | — | $4.49 |
8 rulings from Wizards of the Coast
- 10 November 2023The ability that defines The Mycotyrant's power and toughness works in all zones. As long as The Mycotyrant is on the battlefield (and still a Fungus, or somehow a Saproling), that ability will count The Mycotyrant itself.
- 10 November 2023Abilities that begin with "At the beginning of your end step, if you descended this turn" will trigger only once during your end step, no matter how many times you descended this turn. However, if you haven't descended this turn as your end step begins, the ability won't trigger at all. It's not possible to put a permanent card into your graveyard during the end step in time to have the ability trigger.
- 10 November 2023Multiple cards have abilities that begin with "At the beginning of your end step, if you descended this turn." These cards don't need to have been under your control at the time you descended. For example, if a permanent card is put into your graveyard during your first main phase and you cast Stalactite Stalker your second main phase, its ability will trigger at the beginning of your end step.
- 10 November 2023A permanent card is an artifact, battle, creature, enchantment, land, or planeswalker card. Tokens are not cards, and while tokens are put into the graveyard before ceasing to exist, that action doesn't count as a player having descended.
- 10 November 2023If you control a creature that is both a Fungus and a Saproling, it counts only once for The Mycotyrant's middle ability.
- 10 November 2023Some cards refer to a player who has "descended this turn." This means that a permanent card has been put into that player's graveyard from anywhere this turn.
- 10 November 2023In either case, it doesn't matter if those cards are still in that player's graveyard.
- 10 November 2023Some cards refer to the number of times a player descended this turn. Those cards care about the number of permanent cards put into that player's graveyard from anywhere this turn.