Valve has officially released the 7.21d patch for Dota 2. The move is not a surprise for many fans as IceFrog, the person behind Dota 2, generally releases a patch after certain tournaments. The most recent patch, 7.21c, was released just after the ESL One Katowice 2019.
In terms of General changes, there is only one major adjustment. The Dire hard camp pull has been made easier. Players have long known that pulling has been easier on the Radiant side. With this change, the Dire should get some good laning phases.
For items, four underwent changes. While the recipe cost for Aeon Disk has been lowered to 1100, Guardian Greaves has its costs increased to 1800. Rod of Atos, on the other hand, not only has its cooldown increased to 18 from 16, but cast range has been lowered to 1100 from 1150. Finally, there is Solar Crest, with the target attack speed increased/reduction changed to 80.
Overall, these do not really affect the items that much. For example, Solar Crest sees most players who play support heroes typically stop at Medallion of Courage.
In the case of heroes, Arc Warden received a good buff. Arc Warden's agility gain increased to 2.4 from 2.1. The duration of Arc Warden's Tempest Double has increased to 16/20/24. This had already been increased back in 7.21, and this addition could be a signal for players to try him out.
Drow Ranger obtained a good rework as well, with an agility gain increase to 2.8 and base agiltiy upped by six. Like Arc Warden, this could signal a comeback for the hero, as Dota Buff shows she wasn't even picked during the recently concluded DreamLeague Season 11 Major.
Storm Spirit also got another good rework, with intelligence increasing to 23 + 3.9. Damage from Static Remnant was increased to 120/175/230/285 while the pull distance of Electric Vortex was increased as well to 180/220/260/300. Coupled with the change in 7.21c where Electric Vortex no longer slows the hero, it will be interesting to see how the hero fares in competition.
Oracle was the most picked hero in the recent major, so it's not surprise he experiences some nerfs. In particular, the 7.21d patch makes changes to his False Promise. Cool down has been increased to 115/80/45 with manacost increased to 100/150/200 from 100. Even the case range was rescaled from 1000 and is now 700/850/1000.
Viper has again been nerfed, with agility gain lowered to 2.5. Note that prior to patch 7.21c, Viper had agility gain of 3.3. In 7.21c, Nethertoxin was reworked so that the area-of-effect damage would no longer stack. The mana was also increased to 70/80/90/100 from 75. This time in 7.21d, the cooldown of the skill has been increased to six.
Mars has also been nerfed, something players have been asking for. Strength gain has been lowered to 3.2 from 3.6. The vision AoE for its Spear of Mars has been reduced to 300 from 500. The God's Rebuke skill has its manacost increased to 65/70/75/80 from 55/60/65/70. Finally, Level 20 Talen is no +1s Spears of Mars Stun from +1.5s. This changes should make players happy.
A full list of the changes can be viewed in the 7.21d patch notes.