it would be nice to get to know some of the heroes alongside the tutorial already.
in the first tutorial there are two great opportunities to employ omniknight.

first of all he could serve as a healer next to the shopkeeper and be the one healing the hero instead of the healing salve (which the hero will take to heal on his further journeys).
he can also be the one to explain to the hero what happens when his hp drop to 0.

furthermore he can be the one to safe dragon knight once he drops to 1 hp.
currently the dk cannot fall below 1 hp which is kind of artificial.
why not have omniknight appear once the dk drops below ~50 hp and use guardian angel (infinite duration) while accompaning the dk to the shop keeper.
when the dk doesnt drop on low hp, the omni can be waiting at the shop for him.