My ideal class would be something like Gambler.

Primary healing would be semi-randomized HoTs with more efficient base heals just in case things got bad

Then off global cooldown (Kind of like Mudras) They'd have 1 or 2 "draw" abilities, both with different but fairly high cooldowns. These abilities would give the party buffs depending on what was drawn, and the enemies within a certain range debuffs depending on what was drawn.

This would allow you to gamble, while still being able to heal effectively.