Gathering: speed increase
Infirmary healing: speed increase
Troop Size: increase
Eve is the best healer in the game hands down. You should get her as soon as possible and upgrade her to 211. She not only out-heals everyone else at 44% but her skills add bonus healing in the form of expediting Rage regen rates, and slow heals over 6 rounds.
But wait there is more. Substitute says “has a chance to revive upon death” which implies that it can be any number from 1 to 100, however in my experience she always revives when taking lethal damage. If I had to guess the chance is extremely likely, and for that reason alone she is the best hero you can get. Not only does she heal all the time, but she resists a death blow which can be the difference between losing and full team heal.
If we move on to her Troop skills she increases gathering speed, infirmary healing speed and troop size.
In duels just seeing her in an opponents lineup can be a scary proposition. If she manages to heal and get her Rage regens off consistently, she can heal a team of all its damage faster than you can dish it out.
Mixed with a second healer a team using Eve can be almost unstoppable under the right conditions.
The day the fairies showed up to sprinkle dust on the heroes someone sneezed and Eve became a Goddess.