Guinevere is a King Arthur prestige hero and requires 280,000 prestige to unlock.
Unit Type - Elite Priest: Raises morale of friendly gambit heroes (75% spell hit rate).
Spell - Blessing: Attempts to bless a random friendly gambit hero, raising their morale to 100.
Guinevere is a mid-late game elite support hero. Being an Elite gives her a better unit count. Her stats are amazing for a support hero. Guinevere is the highest tier Priest hero you can obtain for King Arthur players.
She doesn‘t need any Enchanted Items because they won‘t increase her success rate. If you want a better success rate for her try to obtain Rings with Spell Hit Rate. They will massively increase your spell success rate.