Unless stated otherwise, everything here is Diablo II: Resurrected build 3.3.93847, Reign of the Warlock.
Unless stated otherwise, everything here is Diablo II: Resurrected build 3.3.93847, Reign of the Warlock.

Passive: increases life and damage of raised skeletons and revived creatures.
Skeleton Mastery is a level 1 Necromancer passive (Summoning tree, requires Raise Skeleton; it unlocks nothing). It costs no mana and casts nothing: it is a set of four numbers that the three minion skills read when they raise something. Each level gives +8 life to every skeleton and skeletal mage and +2 damage to every skeleton, and +5% life and +10% damage to every revived monster. At level 20 that is +160 life and +40 damage on a skeleton, +160 life on a mage, and +100% life and +200% damage on a revive.
| Level | Monsters: Damage: + | Monsters: Life: + | Skeletons: Life: + | Skeletons: Damage: + | Magi: Life: + |
|---|---|---|---|---|---|
| 1 | 10% | 5% | 8 | 2 | 8 |
| 2 | 20% | 10% | 16 | 4 | 16 |
| 3 | 30% | 15% | 24 | 6 | 24 |
| 4 | 40% | 20% | 32 | 8 | 32 |
| 5 | 50% | 25% | 40 | 10 | 40 |
| 6 | 60% | 30% | 48 | 12 | 48 |
| 7 | 70% | 35% | 56 | 14 | 56 |
| 8 | 80% | 40% | 64 | 16 | 64 |
| 9 | 90% | 45% | 72 | 18 | 72 |
| 10 | 100% | 50% | 80 | 20 | 80 |
| 11 | 110% | 55% | 88 | 22 | 88 |
| 12 | 120% | 60% | 96 | 24 | 96 |
| 13 | 130% | 65% | 104 | 26 | 104 |
| 14 | 140% | 70% | 112 | 28 | 112 |
| 15 | 150% | 75% | 120 | 30 | 120 |
| 16 | 160% | 80% | 128 | 32 | 128 |
| 17 | 170% | 85% | 136 | 34 | 136 |
| 18 | 180% | 90% | 144 | 36 | 144 |
| 19 | 190% | 95% | 152 | 38 | 152 |
| 20 | 200% | 100% | 160 | 40 | 160 |
| 21 | 210% | 105% | 168 | 42 | 168 |
| 22 | 220% | 110% | 176 | 44 | 176 |
| 23 | 230% | 115% | 184 | 46 | 184 |
| 24 | 240% | 120% | 192 | 48 | 192 |
| 25 | 250% | 125% | 200 | 50 | 200 |
| 26 | 260% | 130% | 208 | 52 | 208 |
| 27 | 270% | 135% | 216 | 54 | 216 |
| 28 | 280% | 140% | 224 | 56 | 224 |
| 29 | 290% | 145% | 232 | 58 | 232 |
| 30 | 300% | 150% | 240 | 60 | 240 |
Every line reads lvl, so +skills from items count in full: a +1 from a wand is worth exactly one hard point here.
Skeleton Mastery is a passive state (passivestate "skel_mastery") with no cast. Its four Params are read by the minion skills' own columns, not by the mastery itself:
passivecalc1 for life (Skeleton Mastery level × Param1 × 256) and in passivecalc2 for damage (Skeleton Mastery level × Param2 added to the skeleton's base damage), and adds the mastery's level to its own in the skeleton's attack rating and defense calcs.The Basin states the one rule that matters in play: the bonuses are applied at the time of summoning. A skeleton raised at Skeleton Mastery 20 keeps its +160 life and +40 damage if you then take off the wand that gave the levels, and a skeleton raised at level 0 gains nothing when you put it on. Only a fresh raise reads the new number. The Basin's Raise Skeleton page adds that the mastery's +life is applied before Raise Skeleton's own +% life, so the two multiply; it warns that the in-game tooltip adds them in the wrong order and understates the total.
The mastery does nothing for the golems. Golem Mastery is their equivalent, and Summon Resist covers all of them; a skeleton build and a golem build spend their passive points in different places.
No synergies of its own: Skeleton Mastery has no dsc3 lines and no …SymPerCalc column. It is itself the synergy: Raise Skeleton, Raise Skeletal Mage and Revive each carry a tooltip line that names it. Every one of those reads the mastery's full level (skill('Skeleton Mastery'.lvl)), not its hard points, so +skills from items feed the minions just as hard points do. The Basin lists Marrowwalk, Undead Crown, Arm of King Leoric and the White runeword as sources of +Skeleton Mastery.
Skeleton Mastery never touches a player. What it changes is the life and damage of the minions, and those minions' hits on a player are cut to 17% by the player-versus-player rule as any hit is; see Player versus Player.
lvl, a +skill is worth exactly one hard point here, which is not true of the four golems' cross-synergies, which read each other's hard points (blvl).Written from the game's tables (build 3.3.93847) and the cited pages; a per-level table is computed from skills.txt and skilldesc.txt by the same evaluator the skill pages use. A “legacy rule” is a published engine rule no table proves; a “game table” is read from the table named. · Report incorrect data