Necro Mastery Power

Is Necro Mastery good in Slay the Spire 2?

In Slay the Spire 2, Necro Mastery is a rare power from the Necrobinder card pool. Its effect: Summon 5. Whenever Osty loses HP, ALL enemies lose that much HP as well. Performance-wise it’s a solid if unspectacular include, rated C tier overall.

Over 310 tracked runs its win rate sits at 28.6%, 14.7% ahead of the 13.8% all-deck baseline. It sees niche play, included in only 1.5% of eligible runs. Offer data argues the other way: taken 35.1% of the time it is shown, runs that picked it win 30.8% against 36.6% for runs that passed — a -5.5% pick lift across 253 decided runs. Within Necrobinder runs it’s drafted 8.5% of the time, making it a regular part of that class’s decks. Decks that include it run about 1.1 copies on average.

Its standout pairing so far is Mad Science, which lifts its win rate by +30.0% when the two share a deck. On the relic side, Funerary Mask is its standout companion, worth a +28.1% win-rate swing alongside it. It costs 2 energy, gets upgraded 30.1% of the time, and tends to be picked up near floor 17.

Upgrading the card adds +3 Summon to its stat line. Of the runs that drafted it, 88 ended in victory against 220 deaths and 2 abandons. Its most common run-ender is Test Subject Boss, finishing 8.4% of the runs it shows up in. See the synergies, class split, and threats below for the full picture of where Necro Mastery fits a Necrobinder deck.

Pick or Skip: Necro Mastery

Players take Necro Mastery in 35.1% of the 755 offers it appears in; those runs win 30.8% against 36.6% for runs that passed, a pick lift of -5.5% over 253 decided runs.

Taken 265 times out of 755 offers.

Pick rate when offered counts offers, not runs: out of every time the game put this in front of a player, how often it was taken. It is not the same number as the share of runs that end up containing it.

Pick lift is the sample-adjusted gap between runs that took the option and runs that passed on it. It is the fair way to rank choices, because raw win rates put the smallest samples on top.

When to Pick Up Necro Mastery

Of the 4 pickup windows recorded for Necro Mastery, Act 3 is the best: 71.4% across 21 runs.

Win rate of runs by the act Necro Mastery entered the deck. Acts that have not reached the sample floor show their run count only.

Best Cards to Pair with Necro Mastery

Necro Mastery’s strongest card pairings so far are Mad Science (+30.0%), Legion of Bone (+29.4%), and Shared Fate (+27.6%), each shown with the win-rate lift it adds.

Mad Science+30.0%29 runsLegion of Bone+29.4%26 runsShared Fate+27.6%20 runsDemesne+21.2%56 runsTransfigure+20.9%18 runsSentry Mode+17.8%35 runs

Based on small co-occurring samples — treat these as early signals, not final verdicts.

Necro Mastery Win Rate by Class

Exclusive to the Necrobinder, Necro Mastery posts a 28.4% win rate over 308 tracked runs.

The Necrobinderappears in 8.5% of its runs (308 tracked)

Best Relics for Necro Mastery

The relics that swing Necro Mastery’s win rate the most are Funerary Mask (+28.1%), Book Repair Knife (+24.7%), and Mummified Hand (+22.9%), with each lift shown.

Funerary Mask+28.1%18 runsBook Repair Knife+24.7%16 runsMummified Hand+22.9%15 runsHappy Flower+22.8%54 runsOddly Smooth Stone+22.7%58 runsPendulum+20.4%51 runs

Based on small co-occurring samples — treat these as early signals, not final verdicts.

Necro Mastery Card Details

A 2-energy rare power, Necro Mastery is upgraded 30.1% of the time and tends to enter the deck around floor 17.

Summon 5. Whenever Osty loses HP, ALL enemies lose that much HP as well.

Upgrade: +3 Summon

What Ends Runs with Necro Mastery

Runs holding Necro Mastery end most often against Test Subject Boss (8.4%), Knowledge Demon Boss (5.8%), and Decimillipede Elite (5.5%) — the share of its runs each accounts for is shown.

• Test Subject Boss8.4% of runs
• Knowledge Demon Boss5.8% of runs
• Decimillipede Elite5.5% of runs
• The Insatiable Boss3.5% of runs
• Queen Boss3.5% of runs

See Also

Keep exploring Slay the Spire 2 tier lists and stats below.