Lich Priest is a starter creature, and you shouldn’t try to compare starter creatures to later ones on quality - as the game goes on you’ll naturally acquire more powerful and varied creatures. Brim Smith, as I recall, only comes online in the forth or fifth tier.
That said, if you really want to make Priest viable, here’s a setup:
Lich Priest (2): give them an artifact that focuses on Max HP and any of the Trigger Finger, Siren Charms, or Midnight Feast enchants, all of which of which grant more turns for his ability to trigger on - with high max HP, the attack boosts become considerable.
Depravity Smith: Grants 200% health and luck to all creatures in his row from his artifact. Looks familiar, doesn’t it? If you can swing it, give him the Honed Blades enchant to further boost the Priest’s attack 15% each turn, otherwise just do something supportive and give him Health/Luck boosts, then shove him between the Priests.
Ashwood Ent: Gives all creatures Grace and Mend, keeping your Priests topped off and healing any dings you may take in the meanwhile. Give it the Inspirit enchant, which raises its attack 20% each time something gets healed, and watch it take off; give it defensive enchants to make sure it survives long enough to benefit.
Ruby Paragon: The Defend command raises all your creatures’ current and max HP by 10%, for more Lich Priest shenanigans. Give it either Celestial Furnace or Entanglement so that those defends aren’t wasted; each one will either shear 20% off current HP or have a decent chance to Entangle all enemies.
Thunderstruck Phoenix: Your timebuyer. Give it maximum health / defense, enchant with the Effervescence or Moon Ward abilities for constant Shell, and when it finally goes down it’ll buy you two more turns plus a 30% bonus on attack. I’d suggest Pegasus, but that doesn’t actually keep your creatures in good health, and your Lich Priests are fully capable of killing themselves.