1. Pick Rubick, level Spell Steal and get Aghanim's Scepter (also works without, except with Demonic Purge)
2. Create an enemy Sniper/Broodmother/Shadow Demon/Ember Spirit/Riki
3. Make them use Shrapnel/Spin Web/Demonic Purge/Fire Remnants/Blink Strike
4. Steal the charge-based spell
5. Use up all charges with Rubick, except for the last charge
6. Steal a different spell and then re-steal the charge spell

Result: The charge counter resets for Rubick upon re-gaining the spell, allowing him to use it again multiple times. As long as always 1 charge is left, he can do this infinite times without a cooldown.

Expected: The number of charges he had left are saved. Upon re-stealing the spell, he has as many charges as he had left from previously. It would be also good to make them not continue to re-charge while not having the spell.

NOTE: Although Rubick can never get Stone Remnants, fixing it for that as well could prevent possible future bugs with it.