Oner didn't even need to move to avoid the fires. A simple 'Reflect' and any fire that hit him was taken in by the spell and sent back at the enemy. It barely took any mana for Oner either since the lazily shot fire was easily repelled with a somewhat very weak usage of the Reflect spell, Mana that he was easily able to regain with just a quick moment of meditation, which all it was in this case was Oner closing his eyes, taking in a deep breath, then exhaling, Oner restoring the mana from both the usages of Aura and that usage of Reflect just then, putting him back up to full, which he needed. Normally Oner wouldn't have let down his guard like that, but the enemy wasn't doing anything, so he decided not to let that moment of the stillness of battle be wasted. 

Ascot seemed to move first, moving around the battle field while Amaya summoned Shiva to put a powerful ice attack on the field. Joshua was indeed right. Recklessly attacking an enemy who they knew nothing of probably wasn't the best idea. So instead, Oner got into a stance, powerful Light forming in his Keyblade with a muttered Diaja spell, the blade now looking like one made of solid light as he sat and waited for the enemy, or Ascot, to act, hoping to find an opening within the enemies movements to take advantage of for a decisive strike.