Wand - Convoking wand with +1 of all spell skills gems, +1 of all minion skill gems, as high as possible % increased minion damage, and Minions are aggressive mod.
You can craft this wand by simply buying the base, fracturing the Aggressive mod, or buying it fractured already. Then spam Corroded Fossil + Shuddering Fossil + Metallic Fossil in a 3 socket resonator to get your +2 and % increased minion damage. For the suffixes you want minion crit multi, minion crit chance and a the crafted trigger mod.
Helmet - 
The Dark Monarch (Raised Spectres) will double your specter count, giving you more damage and the ability to boost your Hydras by summoning support specters. MAKE SURE YOU BUY THE SPECTER ONE!!!
Shield - Bitterbind Point WITH +1 to maximum number of Specters is your best in slot. This combined with The Dark Monarch (Raised Spectres) will essentially give you 2 max specters instead of 1.
Gloves - 
Triad Grip with 4 green sockets and +1 socketed gems corruption is your best in slot, making all the physical damage of the Hydra's be converted to cold.
Amulet - Bonemeld is the best in slot here because it gives you 4% increased defences per minion, we have 12 specters, meaning we have 48% increased defenses, bumping our energy shield to the moon alongside our armor. The corrupted implicit "You can apply an additional curse" will be massive for your damage, allowing you to use 
Frostbite and 
Elemental Weakness and 
Sniper's Mark on pinnacle content.
If the corruption is out of your budget, just skip Elemental Weakness and keep Frostbite and Sniper's Mark pathing towards 
Whispers of Doom.
If you can afford the amulet with +1 curse, then you can anoint 
As The Mountain for more block.
Boots - 
Warlock Boots are your best in slot here, being double influenced with +2 to level of all raise spectre gems, which is a Elder mod, and a +3 max fire res which is a Crusader mod.
You can craft these boots by buying a pair of each with the mod you want, either already elevated, or elevate it yourself by using a Orb of Dominance. Once you got the mods you want, then use an Awakener's orb to combine them into one. If you got empty prefix, then you can lock suffixes, scour, and start slamming exalts until you hit good energy shield mods. Remmeber to bench craft Mana to block that mod, and once you got 2 prefixes, craft suffixes cannot be changed, scour, and start again. This can be very expensive.
Rings - For your rings, go for 
Bone Rings with high energy shield rolls, high minion damage rolls, and a lot of Attributes and Resistances. Balance these according to the rest of your gear.
Belt - 
Mageblood will be the best here, as it allows you to negate the downsides of Bonemeld when it comes down to resistances, and providing a lot of quality of life.
Grafts - 
Storming Eshgraft will create Radiant Ground, allowing your Hydra's damage to Lucky.
- 
Replicating Eshgraft will provide you with shocked ground
- make sure to get these grafts with % increased minion damage
Jewels - 3x 
Grand Spectrum (- Minion Crit Multi)
- 
Elegant Hubris (Victario Supreme Grandstanding) near 
The Agnostic for minion damage. I personally use 101540, the hubris can be of any leader, doesn't need to necessary be Victario since you're not taking the keystone.
- Impossible Escape ( The Agnostic) will allow you to take very good nodes for the cost of 1 jewel slot.
- Forbidden Flesh and Flame Combo for 
Void Beacon, giving a good damage boost
- Watcher's Eye with 
Determination reduced damage from crits and 
Discipline energy shield regen mod
- 
Fortress Covenant must be socketed into your large cluster jewel so you don't get the downsides of the jewel, only the upsides.
- 3x 
Large Cluster Jewel. 2 of them with 
Vicious BiteRenewalRotten Claws. and 1 of them with Renewal
Feasting FiendsVicious Bite. Don't take Rotten Claws on the top
Witch
Necromancer
Raise Spectre and 
