Magical tools masters normally can't use magical tools, but Roji realizes that Rio used one to protect Bico. Meanwhile, Muhyo has collapsed after exhausting his ren, leaving him in a dangerous condition of mental numbness... the exact moment Rio has been waiting for.
you'd save a bit of ren and simply 
sleep to recover the rest,
تدّخر قليلاً من الرين
وتنام لاستعادة البقيّة ببساطة وحسب
guardas algo de ren
y dejas que se recupere al descansar,
bisogna lasciare da parte un po' di ren
e recuperare il resto semplicemente dormendo,
você poupa um pouco de ren e
simplesmente dorme para recuperar,
исполнители оставляют
немного рен и ложатся спать.