Rith, Liberated Primeval [Dominaria United] Urza's Destiny Tawnos finally cracked the puzzle:

Tawnos finally cracked the puzzle: the strange structures did not house Mishra's malevolent creations but were themselves among his creations

"Consider the fable of the greedy herder

Set: Ultimate Masters Type: Instant — Arcane Rarity: Rare Cost: {X}{U}{U} You may exile a blue card with mana value X from your hand rather than pay this spell's mana cost

Set: Alpha Edition Type: Sorcery Rarity: Rare Cost: {X}{B} Target player discards X cards at random

Rith, Liberated Primeval [Dominaria United] Urza's Destiny Tawnos finally cracked the puzzle:Set: Dominaria United Type: Legendary Creature Dragon Rarity: Mythic Cost: {2}{R}{G}{W} Flying, ward {2} Other Dragons you control have ward {2}. At the beginning of your end step, if a creature or planeswalker an opponent controlled was dealt excess damage this turn, create a 4 4 red Dragon creature token with flying.