Like most Pokmon cards, the value of Briar depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Stellar Crown)
These are not card-for-card product displays but instead interactive lists of the cards included in the Starter Collection.) White Lyra Dawnbringer Angel of Vitality Make a Stand 2 Ajani's Pridemate Angelic Destiny Charming Prince Felidar Retreat Fumigate Linden, the Steadfast Queen Mentor of the Meek Regal Caracal Zetalpa, Primal Dawn Cat Collector Divine Resilience Joust Through Twinblade Blessing Angel of Finality Resolute Reinforcements Savannah Lions Stroke of Midnight Inspiring Overseer Archway Angel Ballyrush Banneret Crusader of Odric Dawnwing Marshal Devout Decree Disenchant Felidar Cub Knight of Grace Release the Dogs 2 Stasis Snare Syr Alin, the Lion's Claw Valorous Stance 4 Hinterland Sanctifier Lyra Dawnbringer, Angel of Vitality, and Make a Stand are in traditional foil
Warhammer 40K s Callidus Assassin is a baseline 2-for-1 that often gets stronger once you factor in whatever abilities it steals from the creature it copies
Thus far, it seems like everything is fine, but I don't doubt the current structure is taking on considerable weight