Ok, here we go. "Any hunter" means... about 1400 hp hunters who know how to play. I might run out of mana vs double AGM human hunters (or I guess just regular double AGM hunters) before I can do ~1800 damage. I guess I need to explain why again.
No level 20 f2p of any class has the type of burst to kill a Disc priest spamming shields and heals, barring propper usage of CC in combination with very lucky crits that occur at the right times. Please don't assume I mean that priests are invinsible if they're spamming heals on themselves in all situations, this only applies to 1v1. PW:S absorbs 530 damage, Flash Heal restores ~380 hp and Penance heals for ~160 per wave (480 over 2 seconds). If you keep yourself topped off you can't die. The other healing classes can do the same thing (I actually can't speak for druids), HOWEVER, those other classes lack a 40 yard damage spell. Luckily, priests have Mind Blast, which does ~260 damage and has an extremely fast cast time. SW

does like 200 over 18 seconds or something, I'm not entirely sure. You might also be able to get away with trinketing a conc shot and running in range for an offensive Penance for ~330 damage. You can also fear the pet to reduce damage further and avoid getting silenced by a moth or CC'd by one of the other pets if you think you let yourself get too low on hp.
I've never gone oom doing this, but the fight is very long and annoying. And before you bring it up, priest don't beat all classes 1v1, anything that can heal with win the mana war (but again, I can't speak for druids).