Assuming that the player can turn all their lands into a copy of a big creature on their battlefield, they can also easily finish the game
Sidar Jabari of Zhalfir If you really want to play with your red knights like Armory Paladin, Inspiring Veteran, and Stormfist Crusader, build a knights and equipment deck commanded by Syr Gwyn, Hero of Ashvale
Put Sanctum Weaver into your Sythis, Harvests Hand deck, for instance
For three Green mana, you can tutor any creature to your hand, put a land into play tapped, buff a creature while removing an opponent's, or exile an artifact or enchantment
While players might have few rares, they might have several or even many copies of key commons