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. The data flags it as a weaker pick, settling at D tier — usually one to pass on unless your deck specifically wants it.

Over 150 tracked runs its win rate sits at 24.0%, 9.9% ahead of the 14.1% all-deck baseline. It sees niche play, included in only 1.5% of eligible runs. Offer data argues the other way: taken 34.5% of the time it is shown, runs that picked it win 27.5% against 39.8% for runs that passed — a -11.3% pick lift across 120 decided runs. Within Necrobinder runs it’s drafted 8.0% 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 Devour Life, which lifts its win rate by +20.7% when the two share a deck. On the relic side, Strike Dummy is its standout companion, worth a +18.8% win-rate swing alongside it. It costs 2 energy, gets upgraded 32.5% 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, 36 ended in victory against 114 deaths and 0 abandons. Its most common run-ender is Decimillipede Elite, finishing 8.7% 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 34.5% of the 368 offers it appears in; those runs win 27.5% against 39.8% for runs that passed, a pick lift of -11.3% over 120 decided runs.

Taken 127 times out of 368 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 3 pickup windows recorded for Necro Mastery, Act 3 is the best: 70.0% across 10 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 Devour Life (+20.7%), Haunt (+20.0%), and Sentry Mode (+19.9%), each shown with the win-rate lift it adds.

Devour Life+20.7%20 runsHaunt+20.0%25 runsSentry Mode+19.9%16 runsReanimate+18.1%29 runsRight Hand Hand+15.5%29 runsDemesne+14.5%17 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 24.2% win rate over 149 tracked runs.

The Necrobinderappears in 8.0% of its runs (149 tracked)

Best Relics for Necro Mastery

The relics that swing Necro Mastery’s win rate the most are Strike Dummy (+18.8%), Lasting Candy (+17.6%), and Candelabra (+16.7%), with each lift shown.

Strike Dummy+18.8%19 runsLasting Candy+17.6%15 runsCandelabra+16.7%18 runsOddly Smooth Stone+16.6%23 runsBag of Preparation+16.0%21 runsLantern+14.8%22 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 32.5% 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 Decimillipede Elite (8.7%), Test Subject Boss (7.3%), and Entomancer Elite (5.3%) — the share of its runs each accounts for is shown.

• Decimillipede Elite8.7% of runs
• Test Subject Boss7.3% of runs
• Entomancer Elite5.3% of runs
• Queen Boss4.7% of runs
• Knowledge Demon Boss4.0% of runs

See Also

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