Just doing my first explorable run in Arah and just beat the 3rd boss - Giganticus Lupicus. 3 Phases. First phase - prevent Boss from buffing up by eating risen grubs. Second phase - movement movement movement. Third phase - even more movement. 10-15 minutes high concentration encounter. Epic.
Add videos and stories about PvE stuff, to dispel the rumour GW2 is too casual.