I don't see why it should not work.
How many of those 4 chars will be active? You also want to consider if you will be fighting aggressive mobs who suddenly switch target (mobs in dragon zones in particular will root/mez/stun your focus pet and switch target to your healer). This can be difficult to counter if you are controlling multiple chars by yourself.
- The necro has some obvious advantages. It does not need a guard bot and is mez/root immune.
- The bainshee provides very consistent damage output and requires little interaction (needs someone to guard it though).
- The warden is probably the best guard class. Guard + pbt + fonts + healing.
- The nature druid has an awesome ablative buff (not much else though).
- The mentalist is also great support for a focus pet, but it is vulnerable.
- The cleric/friar has defensive heal procs.
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[Hib] Druid - Blademaster - Bard - Mentalist