I think it'd be cool if battlewardens hung out at the aetherytes and nodes and gave any party that asked them a behest-like thing. SP wouldn't be boosted and mobs wouldn't be instanced but it'd be stuff like

Kill 3 Efts in 5 minutes. If you succeed, you get a new goal and the timer is reset. The goals would get harder and harder and you'd get a bonus (SP, tokens for whatever, Guardian's Favor, whatever) depending on how many of the goals you could complete before running out of time. Every 3rd or so success they could give you a full party heal/mana restore and maybe a speed buff every other one. Stuff like that. It'd keep parties moving and active and probably fun.