The actual mechanics are a little tricky. I might be wrong, but I think avalanche checks to see if it's target is tossed or not. I'm going with this rather than the reverse since the combat log shows the avalanche damage increasing, rather than it being from a different source. If the check is a positive, then it adds another tick of avalanche damage.
It checks this every 0.25 seconds, toss lasts 1.02 seconds, so normally if you time it properly you will get 4 extra ticks of avalanche damage, but that extra 0.02 seconds makes it possible to get 1 more additional tick in, resulting in that 2.25x ava dmg.
edited my post a bit since I'm not 100% sure about everything.
I'm trying to do research but there isn't much about this in dota 2. And running tests would be really time consuming since I would need a pretty large sample to check for that extra 0.25x damage, if it still exists.
Found this from 2009. dota 1 mechanics ofc.
Quote:
Originally Posted by 3DM@rk
The bonus damage (aka the "second avalanche") is not dealt all at once, but in four parts every 0.25 seconds. The unit will be receiving the bonus damage simultaneously with the standard Avalanche damage as long as it both tossed and in the Avalanche AoE.
Therefore it is better to cast avalanche first, because you want to have the target under the effect of both spells as long as possible. Toss lasts only for 1.02 seconds, while Avalanche checks for a tossed target every 0.25 seconds, up to seven times (1.75 sec. time window). So you can Toss the target up to 0.75 seconds after Avalanche and still deal full bonus damage.
Also, with this setup (Ava -> Toss), you can deal one more wave of the bonus damage, if you manage to put Toss into a 0.02 time interval before the bonus damage check for Ava is performed. This can result in "2.25x Avalanche" instead of 2x.
Last edited by Count Chocula; 04-03-2013 at 11:31 PM.