In reading and responding to this thread, I must remind myself that no game on earth would consider allowing a City of Heroes level of Support: Buff, Debuff, Crowd Control. Lets be honest, our CC is pretty mediocre.

So lets think usefully here. Buffs, let's steal from the Log Horizon anime, or FF9: could we cast Enthunder on the tank, so he earns more enimity, or Envenom on a Damage Dealer? Debuffs: Armor Break, Magic Break, Paralyze or Slow with a duration close to that from FF11. Crowd Control: could we have an honest to goodness non-fragile Immobilize? The mob has his ranged attacks, he has his melee, but he's nailed down to one spot and not galumphing about after the squishies. I know better than to even dream of a Hold.

A solid support character should be a force multiplier for his party, not just offer a slight edge that could easily be ignored if you filled his spot with another Blackmage.