Shyren is a cheap card with a good ability, making her useful with all soul types. As when placed, she will heal 5 HP to a target of your choice, including enemies and players. This makes Shyren the all-class version of Kindness's Heal (but with 2 more HP and no card draw).
Because of this, Shyren is especially useful in the Kindness deck and one should be kept in hand for later in game. She can also be combined with Feast in order to deal 5 damage to an enemy, enough to kill cards like Mad Dummy.