It gives you pump and lifelink for your tribal creatures along with more creature tokens that do damage when they die
Ajani Vengeant Armageddon Bear Umbra Bend or Break Bontu's Last Reckoning Boom // Bust Catastrophe Chaos Orb Cleansing Decree of Annihilation Desolation Angel Devastation Elspeth Tirel Eye of Singularity Fall of the Thran From the Ashes Impending Disaster Jalum Grifter Jokulhaups Landfill Mine Layer Myojin of Infinite Rage Obliterate Ravages of War Ruination Scourglass Solar Tide Strategy, Schmategy The Argent Etchings Urza's Sylex Wake of Destruction Winter's Chill Wrath of Leknif (playtest) Zacama, Primal Calamity
These are cards such as Shelinda, Yevon AcolyteShelinda, Yevon Acolyte, Tromell, Seymour's ButlerTromell, Seymour's Butler, or Rosa, Resolute White MageRosa, Resolute White Mage
If that were the only text on the sacrifice effect, wed probably consider running this
Youd better hope the first spell you cast into Kaervek is removal that kills a 5/4 or youre in trouble
White MTG Token Doublers The first set of MTG token doublers up for discussion are the mono white ones