9 cards where the card types include “creature” and the mana value >= 6 and the set is “m21” and (the rarity is equal to common or the rarity is equal to uncommon)

Bone Pit Brute (Core Set 2021 #132)
Colossal Dreadmaw (Core Set 2021 #176)
Gloom Sower (Core Set 2021 #100)
Goremand (Core Set 2021 #101)
Hellkite Punisher (Core Set 2021 #151)
Spined Megalodon (Core Set 2021 #72)
Tolarian Kraken (Core Set 2021 #80)
Waker of Waves (Core Set 2021 #84)
Warden of the Woods (Core Set 2021 #213)

The message was clear to Sorin—time to search for something else.