(Although, honorable mention to Squandered Resources, arguably the best of that lot)
Here are the percentages: (note when I say "rare" below, I mean rare or mythic rare) Common, common will happen 49% of the time
Creatures you control gain menace and trample until end of turn

Academy Loremaster Advanced Reconstruction Alabaster Leech Andradite Leech Anointed Peacekeeper Arachne, Psionic Weaver Aura of Silence Aven Interrupter Because I Have Willed It Boreal Elemental Callaphe, Beloved of the Sea Captain Eberhart Case of the Ransacked Lab Charitable Levy Charix, the Raging Isle Chatzuk, Mighty Guitarist (playtest) Chill Curse of Silence Defense Grid Derelor Disruptor Flute Dovin, Hand of Control Elderwood Scion Elspeth Conquers Death Emet-Selch of the Third Seat Esior, Wardwing Familiar Eureka Exiled Doomsayer Feroz's Ban Finale of Promise Fires of Invention Geist-Fueled Scarecrow Gloom Glowrider God-Pharaoh's Statue Gonti, Canny Acquisitor Gran-Gran Grand Arbiter Augustin IV High Seas Hinata, Dawn-Crowned Icefall Regent Irini Sengir Jade Leech Jubilant Skybonder Kaervek's Torch Kasmina, Enigmatic Mentor Killian, Ink Duelist Kopala, Warden of Waves Krallenhorde Howler Krosan Drover Loan Shark Lodestone Golem Lyse Hext Mindbreak Trap Monastery Siege Nogi, Draco-Zealot Paladin Class Primal Amulet Pursued Whale Reidane, God of the Worthy Rowan, Scholar of Sparks Ruby Leech Sapphire Leech Sphere of Resistance Sphinx of New Prahv Squeeze Syr Elenora, the Discerning Talent of the Telepath Tax Collector Thalia, Guardian of Thraben The Earth Crystal The Ur-Dragon

The Watcher in the Water It isnt hard to trigger The Watcher in the Waters token making ability
[F][C][C] Direct Arrow: This attack does 80 damage to 1 of your opponents Pokmon