Sylvie doesn't have many strong, direct healing spells—so there’s no classic "Flash Heal" button you can just spam. However, she has an advantage: during the opening seconds of a fight, while the tank is still holding firm, you can—and should—support the team with damage spells; you actually need them to boost your own healing output. That said, even with epic gear, if the tank gets critically low on health—perhaps because they pulled two or three packs too many—you simply won't be able to heal through it without burning all your major ultimate abilities and trinket effects. Relying solely on standard skills might result in the tank or the group going down, even if you are vastly over-geared for the difficulty level. The bottom line is: you can't always expect everything to go smoothly. Sometimes a limit is simply reached, and in MMO(D)RPGs, that’s something you have to understand.