This build works well, with inexpensive gear options while remaining viable. He is a strong early ladder option in which you can’t depend on accumulated wealth and stashed D2 Resurrected Items. Likewise, he is able to be viable in Hardcore using the right gear selection. The varied damage sources imply that he won’t want to use Sunder Charms to stay effective and won’t have to offset negative resistances. As a PvM Character, your effective clear speed is going to be on par with higher-cost builds and can require considerably less optimization to stay effective (because of Corpse Explosion damage scaling separately from skill or gear investment).
The emphasis of the build is on life, mobility, powerful bone attacks which are rarely negated, corpse explosion, curses to amplify damage, and summons to do something as a shield and supply additional physical damage.
Attributes
Enough strength and dexterity for the selected gear, the remainder in vitality.
Skills
You possess some autonomy here, based on your preferred playstyle. A summon primary build will afford more tackiness to minions and therefore more safety. However, it'll lack the initial clear speed of the bone primary build. Summon primary is usually recommended for Hardcore. Buying d2 resurrected items and diablo 4 items can help boost your gear in D2R Ladder, which benefits physical damage dealers and specs that benefit from scaling.
Bone Tree
There are three primary bone attacks you are able to choose from. Teeth, Bone Spear, and Bone Spirit. If you are Bone Primary, it is usually recommended you invest 40-60 points within this tree. If you are Summon primary, max one bone spell and invest some points in necessary prerequisites. Invest one in all other synergies (Bone Wall and Bone Prison).
Curse Tree
One point each inside your desired curse(s). Amplify damage necessitates the least skill investment (just one point) and offers ample damage amplification for minions, corpse explosion as well as your mercenary. Decrepify and Dim Vision can offer additional safety for Hardcore.
Summon Tree
Your remaining Skill points are going to be used on Summons. A Golemancer build might be viable but isn't recommended like a single Golem won't be as effective as dispersing damage. An Iron Golem will, however, be part of an aura. 1 Point in Revive, Skeletal Mages, Golem Mastery, each Golem, and Summon Resistances. Next max Skeletal Mastery, then Skeletal Warriors.
Iron Golem Aura
Insight - This is going to be a cheap option that ought to alleviate the want to use mana potions.
Pride - This can be considered for any high-cost build, and in which you are not utilizing an A2 Pride mercenary.
Bramble - Another viable option providing a thorns aura for your army when you're not by using this on an A2 mercenary.
Gear
Helm:
Shako - Best overall caster helm where FCR isn't required
Crown of Ages - Best defensive selection for Hardcore
Amulet:
Maras - Best for softcore and Hardcore (FCR isn't required with this build)
Weapon:
Heart from the Oak - Best overall caster weapon for Bone Primary build
BeastZ - Best minion buffer for Summon Primary build
Bone Wand - A strong offensive-orientated selection for Bone Primary build
Rings:
Bul Kathos is usually recommended. Stone of Jordan is viable.
Shield:
Spirit Monarch - The best standard caster option otherwise opt for max block
Homunculus - A strong max block option
Darkforce - A good overall option
Stormshield - The best defensive selection for Hardcore (note: you cap out at 50% damage reduction, that is something to bear in mind if also utilizing Crown of Ages).
Armor:
Enigma - The strongest selection for any game mode, offering teleport repositioning for the army, in addition to arguably the strongest general buffs from armor options.
Vipermagi or any other + skill armors that offer defensive stats can be viewed as budget options.