The Formless Clone was indeed convenient, but its limitations were also enormous.
It could only replicate five abilities of the original body, and for this lone journey to investigate the Bear Goblins, Gu Ran had chosen the following five abilities: Dark Hider, Flame Demon Transformation, Purgatory Devil Flame, Eye of Insight, and Positioning Teleport.
(PS: Because many fans responded that the Formless Clone was too overpowered, I've made some adjustments in the previous text, so it can only replicate five abilities of the original body.)
The Dark Hider was for stealthy intrusion while the Flame Demon Transformation was for emergencies, a powerful move in case of unexpected situations. The Purgatory Devil Flame, Eye of Insight, and Positioning Teleport were naturally for ensuring the acquisition of the desired information.
That was also the reason why he could no longer conjure a weapon, leading to the current situation where he was passively taking hits.