18 cards where the card types include “creature” and the mana value = 1 and the text includes “{t}: add”

Avacyn's Pilgrim (Midnight Hunt Commander #132)
Birds of Paradise (Ravnica Remastered #133)
Boreal Druid (Coldsnap #105)
Ceta Disciple (Apocalypse #19)
Delighted Halfling (The Lord of the Rings: Tales of Middle-earth #158)
Elves of Deep Shadow (Duel Decks: Izzet vs. Golgari #47)
Elvish Mystic (Commander Masters #284)
Fyndhorn Elves (Commander Legends #228)
Honored Hierarch (Magic Origins #182)
Ignoble Hierarch (Modern Horizons 2 #166)
Ixalli's Lorekeeper (The Lost Caverns of Ixalan #194)
Joraga Treespeaker (Rise of the Eldrazi #190)
Llanowar Elves (Game Night #46)
Llanowar Mentor (Time Spiral Remastered #216)
Necra Disciple (Apocalypse #44)
Noble Hierarch (Double Masters #177)
Omen Hawker (March of the Machine #70)
Viridian Acolyte (Darksteel #89)

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