Dota 2 received the new patch 7.21 with the New Ranked Season and it was supposed to be balancing patch. 7.20 was the Major Patch and like all other major patches 7.20 changed the game again, 7.21 is here now to shape the meta and the heroes properly.
I am not going to talk about most buffed or most powerful heroes, I am going to mention 10 heroes that made a profit from 7.21 and now in a better position with an increased win rate.
Alchemist's win rate rocketed up after 7.21 by almost 5%. He now might be meta-viable with a little over 52% win rate. Alchemist did well at the end of the patch and it's because icefrog improved a lot of stuff. His base movement speed was increased by 10, base agility was increased to 22 from 16. Chemical rage base attack time was improved and level concoction talent now adds the damage to the max instead of the base damage. So a lot of positive changes and that makes him relatively better.
Monkey King saw a very little improvement and almost no changes in the patch which makes him almost meta viable. But it's not about how many improvements he had if he receives the improvement in the right area. He can be very dangerous even with slight buffs. Monkey King's base movement speed was increased by 5 and Wokung's Command attack rate improved from 1.3 to 1.2. A small buff on a hero that was already having over 45% win rate, now with a slight increase he is sitting at almost a 50% win rate.
Brood Mother faced a few reworks but after reworks, she received increased win rate which is now pushing her over 50% win rate. Her level 10 talent-spawn spiderling damage saw a huge buff as the damage increased from 75 to now 125. Broodmother level 15 talent changed from XP gain to +15 agility, I see it as a buff.?Level 20 talent increased from 20 spider damage to 30. Level 25 talent increased from 350 spider's health to 450. All the reworks were positive changes and this explains the improvement in the win rate. I'd say Brood is more than meta viable at this point.