While both of Yuna's abilities can be played for value, her second ability leans into the graveyard for extra utility and resilience
There are far better rat Commanders out there, but especially since he has the rat type himself, he slots nicely in as a supplemental include
The next time this creature would be destroyed this turn, it isnt
Maralen of the Mornsong Avatar Markov Purifier Mask of Griselbrand Miara, Thorn of the Glade My Genius Knows No Bounds Nafs Asp Necrodominance Necrologia Necropotence Nihilistic Glee Nurturing Peatland Oloro, Ageless Ascetic Phyrexian Etchings Power Taint Promise of Power Raiders' Spoils Rejuvenate Sanguine Spy Seymour Flux Shanna, Purifying Blade Shessra, Death's Whisper Silent Clearing Sinister Monolith Sphinx of the Revelation Staff of Compleation Stirge Street Wraith Sunbaked Canyon Susur Secundi, Void Altar Sylvan Library Syndicate Heavy Tenacious Underdog The Last Ride Tolarian Geyser Trading Post
For one mana, you get an artifact that you can then pay two mana and tap to give a creature pseudo-vigilance
Then discard a card unless there are three or more Lesson cards in your graveyard