At the minimum, Criterion should have a weekly token that can traded for a twine/shine or 2 tokens for a twine and 1 for a shine. This would keep people doing it beyond the initial clear/10 clears for the mount.

As for Criterion Savage, considering how long it takes to gear up alt classes (37 weeks for all roles and that's with supplementing with Savage gear), a weekly token that can be used to trade for a single tomestone piece of gear, 1 token for accessories, 2 for head/hands/feet, 3 for body/legs.

The difficulty alone will make it so not everyone will be able to get the rewards but it will increase engagement with the content while also letting players gear up alt classes faster that they can then use to help with other content.