Druid: Remedy + Recovery
Bishop: Heal/Flash of Light + Soul Strike
Sorcerer: Fireball/Water Globes + Lightning Strike
Necromancer: Fireball + Detonating Bones
Crusader: Shield Throw + Crucify
Psion: Twisting Metal + Liquified Arms + Enslave + Psionic Blade spell if you so choose.
Seems to me like each caster class 'only' casts two spells. Most peoples Sorcerers only cast one spell even. If anything, haste benefits Druid THE MOST because it has zero damage mitigation spells like Bishop, so a druid has to actively heal any group members that take damage from enemy AOE spells. A Bishop through rotating mends and divine protections can heal the entire group without needing to use its actual casting skills. A druid needs to be able to rotate remedies through the party at a quick pace, so the faster that the druid can get multiple remedy ticks off, the better it is for healing a group by itself.