They are not common, and rather difficult to find
Wall of Blossoms (Ext, S, Block) The highest placing true cantrip on the list, Wall of Blossoms plays defense with the best of them, without costing you a single card
So I looked for complete sets on eBay
As such, it's easy to find a way to return Thousand-Faced Shadow to hand so that it can copy another attacking creature later on

Scyther #87 (Shiny/ One Rainbow Star) Pineco #88 (Shiny/ One Rainbow Star) Phantump #89 (Shiny/ One Rainbow Star) Trevanant #90 (Shiny/ One Rainbow Star) Charmander #91 (Shiny/ One Rainbow Star) Charmeleon #92 (Shiny/ One Rainbow Star) Ponyta #93 (Shiny/ One Rainbow Star) Rapidash #94 (Shiny/ One Rainbow Star) Slowpoke #95 (Shiny/ One Rainbow Star) Pikachu #96 (Shiny/ One Rainbow Star) Raichu #97 (Shiny/ One Rainbow Star) Electrike #98 (Shiny/ One Rainbow Star) Hawlucha #99 (Shiny/ One Rainbow Star) Gastly #100 (Shiny/ One Rainbow Star) Haunter #101 (Shiny/ One Rainbow Star) Zorua #102 (Shiny/ One Rainbow Star) Zoroark #103 (Shiny/ One Rainbow Star) Forretress #104 (Shiny/ One Rainbow Star) Dratini #105 (Shiny/ One Rainbow Star) Dragonair #106 (Shiny/ One Rainbow Star) Dragonite #107 (Shiny/ One Rainbow Star) Axew #108 (Shiny/ One Rainbow Star) Fraxure #109 (Shiny/ One Rainbow Star) Haxorus #110 (Shiny/ One Rainbow Star) Rewards: 36 Wonder Hourglasses, 12 Pack Hourglasses and 10 Shop Tickets

Helpful Hunter Heres another white creature that cantrips when it enters, and honestly, Im gonna level with you: unless youre leveraging the fact that Helpful Hunter is a Cat, Wall of Omens has yet to be beat