DotA's 6.79 patch, likely to come to Dota 2 down the line, has had its patch notes released and to say they're expansive is a huge understatement. We're talking about changes, small and large, to most heroes and multiple core aspects of the game to boot. I... I don't even know where to begin. The best place to start, I suppose, would be to point you to the patch notes and tell you to start reading. Just go.
Some of the most dramatic hero changes have happened to Broodmother and Slark. For instance, Broodmother's spin web now will no longer destroy trees -- it doesn't have to! Instead, where Broodmother's web is laid down she has free movement and that includes over trees and cliffs. The tradeoff for less direct map effects will be a wider AoE and longer cast distance. Slark, on the other hand, got a pretty handy nerf to his Shadow Dance ability, with the duration cut from 5.5 seconds to 4, and the cooldown more than doubled from 25 seconds to 65! In trade-off, however, Shadow Dance will no longer be revealed by Truesight. Crazy.
Those are just two of the more dramatic changes from a list of changes made to almost every single hero. Pudge can now use Blink Dagger; Riki can cast spells and use items without being revealed; Alchemist no longer gets bonus HP from his ult and instead gets a ton more HP regen. That's just the tip of the iceberg! I' not even going to start on items and general gameplay mechanics.
Get ready for a DotA meta shift, everybody. I can feel it.