I can't really consider it a "combo", at least not the same way I'd consider Force Staff+Remote Mines, Blink+Echo Slam or any other comboes you may remember.
Because by mixing the skills I get a result wich wouldn't be available at any other conditions, and won't work with any other hero.
So, how to fix it?
The answer: Mekansm-like mech
1. Unit is in Avalanche AoE
2. (Saving for later)
3. Unit takes damage and stun
4. Unit gets a debuff for 1 second
5. Unit is Tossed and takes all its effects
6. Unit falls on Avalanche AoE again
7. and 2. Check for Debuff mentioned on item 4
8. If debuff is present, unit doesn't take damage/get stunned
Balance numbers if needed.