WD creates a lot of lane impact. Thanks to his skill combinations, good start characteristics, and long attack range, WD can strangle and harass opponents. Moreover, the super initial solid nuke Maledict grants the hero 100% frag if enemies make a mistake. Maledict deals unfair damage, not only in combination with damage from allies but also with Death Ward alone. WD is a good healer - Voodoo Restoration, which, despite the "modest" HP regen index, is effective due to the lack of a cooldown.
Witch Doctor suffers from a bit of strength and agility rate increase. If there are no problems with intelligence, then the lack of HP and armor is a significant disadvantage. His ultimate spell Death Ward can be interrupted, and it's minus. If Witch Doctor gets stunned or silenced during the Death Ward cast, his contribution to the team drops rapidly. Therefore, one of the best counters for WD is Silencer, Drow Ranger, Puck, or any hero with a mass disable. In addition, you can reduce Maledict damage with healing. So, any hero with lifesteal isn't afraid of WD.
Initially, we take as much as possible Tango, Healing Salve, and Mango for yourself and carry. By the way, mana regen items are not so useful for WD since he doesn't need to spam skills. From level 3, you can start making frags by maxing Paralyzing Cask to 1 and Maledict to 2. Maledict level 1 does too little damage, but at the second level, it is already enough to kill the affected hero. Voodoo Restoration is usually ignored and maxed on level 4 because it consumes too much mana and grants minor HP regen points. Also, don't forget to stack creeps, harass opponents, and place wards on your jungle to secure unexpected gangs. Before the 20-minute, try to purchase Arcane Boots, Magic Stick, Urn of Shadows, and Glimmer Cape.
Attempt to participate in fights and help allies as much as possible. Paralyzing Cask is very annoying to nearby enemies, just like Maledict. A successful Death Ward can deal massive damage to low-armor heroes, while a Voodoo Restoration can regenerate allies and creeps. If vulnerable enemy farms in the lane next to the creeps, and his team is far away, WD can kill him solo with Cask + Maledict + Death Ward combo, only if he hasn't BKB or birth escape. It's enough to bounce a couple of times from the creeps into the hero, and then Death Ward and Maledict will already do their "filth" job. In mass fights, due to the short range of skill cast and Death Ward attack range, it can be challenging to keep a safe position. Therefore, in 5x5 fights, when you cast Ultimate, it is better to use Glimmer before and, if necessary, to activate a second spell that does not knock down the Death Ward.
Late game Witch Doctor follows close to the team. If WD has Aghanim's Scepter, then he transforms into a dangerous "Death Machine" for the entire enemy team. A well-timed Death Ward through hidden positions can wipe out a full opponent's team. In addition, the Maledict remains extremely dangerous even in the final stage of the match. Remember that it doesn't deal instant damage and doesn't drop from heroes affected by BKB or spell immunity dispel. Even after Black King Bar's end, opponents will continue to receive damage from Maledict.
It seems that Witch Doctor is gradually returning to the mainstream even though he has little popularity in Competitive Dota. He is a frequent guest in public because he doesn't have so many counter-picks. Therefore, Witch Doctor can be a very effective pos-5 support with the right play.