reduce housing space on healer and valk
these two are the most underused troops in coc.
i just used healers around 5 times during my 4 months playing coc.
they are pretty useless in th8-10 given numerous traps and powerful air defense and point attacks.
reducing their housing space from 14 to 12 will be the first option. (and i believe will not be to op)
adding an additional lvl will do too.
another option will be they can heal air units which makes loonions more effective.
for the valk. even when the training time reduce, still very few used them. though its ai is now ok. housing space is still very huge