Wouldn't a skill like BLU's Sticky Tongue be cool for tanks?

[Dzonathan]

Especially with how caster enemies work in this game. Sure you can technically interrupt them but you have at best maybe 1 server tick to move them before they just start casting again.

In other games they are usually locked out of that spell for at least 8 seconds and resort to auto attacks during that time, which means they will follow you.

Here's more simple solution:
1) Approach the pack in such a way that most melee mobs are between you and the caster
2) Cast a single AoE spell to get aggro on melee mobs as you run through them
3) Get close to the caster and continue your AoE rotation
4) ???
5) Problem solved