26 cards where the text includes “level up”

Beastbreaker of Bala Ged (Duel Decks: Zendikar vs. Eldrazi #10)
Brimstone Mage (Rise of the Eldrazi #137)
Caravan Escort (Duel Decks: Zendikar vs. Eldrazi #3)
Coralhelm Commander (The Lost Caverns of Ixalan Commander #148)
Echo Mage (Commander 2013 #43)
Enclave Cryptologist (Rise of the Eldrazi #66)
Guul Draz Assassin (Rise of the Eldrazi #112)
Hada Spy Patrol (Commander Anthology #40)
Halimar Wavewatch (Rise of the Eldrazi #72)
Hedron-Field Purists (Rise of the Eldrazi #25)
Hexdrinker (Modern Horizons #168)
Ikiral Outrider (Rise of the Eldrazi #27)
Joraga Treespeaker (Rise of the Eldrazi #190)
Kabira Vindicator (Duel Decks: Zendikar vs. Eldrazi #4)
Kargan Dragonlord (Rise of the Eldrazi #152)
Kazandu Tuskcaller (Commander 2021 #196)
Knight of Cliffhaven (Duel Decks: Zendikar vs. Eldrazi #5)
Lighthouse Chronologist (Rise of the Eldrazi #75)
Lord of Shatterskull Pass (Rise of the Eldrazi #156)
Nirkana Cutthroat (Rise of the Eldrazi #119)
Null Champion (Rise of the Eldrazi #121)
Skywatcher Adept (Rise of the Eldrazi #88)
Student of Warfare (Rise of the Eldrazi #47)
Transcendent Master (Rise of the Eldrazi #51)
Venerated Teacher (Rise of the Eldrazi #93)
Zulaport Enforcer (Rise of the Eldrazi #133)

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