If you want to try out a companion but want to keep the deck building easy I suggest picking up the Painbow precon from Dominaria United
Of course, there is still risk
Magic Online might be ugly and buggy, but it does more or less do its job
Akim, the Soaring Wind Bonehoard Dracosaur Carnage Tyrant Deathmist Raptor Ghalta, Stampede Tyrant Gishath, Sun's Avatar Illuna, Apex of Wishes Illuna, Apex of Wishes Kalamax, the Stormsire Pantlaza, Sun-Favored Polyraptor Ravenous Tyrannosaurus Sauron, Dino Devotee Silverclad Ferocidons Snapdax, Apex of the Hunt Snapdax, Apex of the Hunt The Tarrasque Thrasta, Tempest's Roar Trapjaw Tyrant Triceraton Commander Tyrranax Rex Vadrok, Apex of Thunder Vadrok, Apex of Thunder Vaultborn Tyrant Wakening Sun's Avatar Zacama, Primal Calamity Zilortha, Strength Incarnate
Use Rograkh to trigger effects or carry equipment rather than as a damage source