Since the number of tokens required to upgrade champions are so high i would suggest that all elite players kan exchange atleast 100 tokens or more. Making 37 exchanges at a time it would take ages for it to have any effect.
Also since materials are so precious it would be good to have an option to request these also. For example changing fire for water or fire for chippy tokens or just donating.
I hope you will consider this?
Agree with what Summertroll is suggesting. Materials very very precious now and also we are in huge demand of materials for the upgrades. it would be great if we can donate and share the materials as well, similarly like tokens.