For each opponent who does, you gain protection from that player until your next turn." (You can't be targeted, dealt damage, or enchanted by anything controlled by that player.) Protection from a player means that you have protection from each object controlled by that player

Aesi, Tyrant of Gyre Strait Azusa's Many Journeys Beanstalk Wurm Beanstalk Wurm Case of the Locked Hothouse Druid Class Dryad of the Ilysian Grove Enter the Unknown Escape to the Wilds Exploration Exploration Broodship Explore Flubs, the Fool Gaea's Touch Ghirapur Orrery Hearthhull, the Worldseed Hugs, Grisly Guardian Icetill Explorer Kellan, Inquisitive Prodigy Kellan, Inquisitive Prodigy Kiora, the Crashing Wave Loot, Exuberant Explorer Mina and Denn, Wildborn My Tendrils Run Deep Oracle of Mul Daya Prismatic Undercurrents Rites of Flourishing Scale the Heights Song of Creation Storm Cauldron Sword of Forge and Frontier Thalia and The Gitrog Monster The Gitrog Monster This World Belongs to Me Titania Two Streams Facility Urban Evolution Wayward Swordtooth Zell Dincht
If youre just starting out in MTG Arena or MTG, keep your creatures and spells cheap and just go for all-out aggression
Creatures like Goldvein Hydra and Pawpatch Recruit scale in power later in the game