Slay the Spire 2 Co-op Guide: How to Host, Join and Share a Run

Slay the Spire 2 co-op in one paragraph

Slay the Spire 2 co-op is online only, Steam only, and friends only. Up to four players climb the same Spire together from Multiplayer → Host or Multiplayer → Join, and everyone must be on the host’s Steam friends list — there is no matchmaking, no lobby browser and no password system. The party shares the map, the fights and the nodes; each player keeps a separate deck, hand, energy, HP, gold and potions. Relics drop as party loot and then get assigned to one player. Enemy health pools grow with every extra body in the party, so four players is not easy mode. The game is still in Early Access as of late July 2026, and multiplayer is the part Mega Crit has been patching hardest — beta build v0.108.0 (2 July 2026) added fifteen multiplayer-only cards, and v0.109.0 (17 July 2026) followed two weeks later.

What state is the game actually in?

Worth pinning down before you commit a group to a long campaign. Slay the Spire 2 entered Steam Early Access on 5 March 2026 for Windows, macOS and Linux, and it is Steam Deck Verified. Mega Crit’s stated plan is roughly one to two years of Early Access, which puts 1.0 somewhere in 2027–2028. There are no console versions and no crossplay; every reference to co-op in official messaging is a Steam reference.

That also means the mode is a moving target. The multiplayer card pool, the enemy scaling numbers and the co-op UI have all been touched by patches in 2026, and the beta branch usually gets them weeks before the main branch. If your group is mid-campaign, check the patch notes before anyone updates — balance shifts land in the middle of runs.

Co-op basics at a glance

• 2–4 players total (host plus up to three guests).
• Online only. No local split-screen, no LAN, no couch co-op.
• PC only during Early Access — Windows, macOS, Linux, Steam Deck.
• Steam friends only. No public matchmaking, no lobby browser, no passwords.
• The host creates the multiplayer save; guests join into that run.
• Each player keeps their own deck, hand, energy, HP, gold and potions.
• The map, node path, encounters and campfires are shared.
• Enemy HP pools scale up with player count.
• No drop-in joining. The party roster is fixed when the run starts.

How to host a co-op run

Before you start

• Everyone owns Slay the Spire 2 on Steam and is online.
• Everyone is on the host’s Steam friends list. This is a hard requirement, not a convenience.
• The host decides which save the campaign lives on, because the run is stored there.

The flow

• From the title screen pick Multiplayer, then Host. This creates a multiplayer save.
• Use the lobby’s Invite button, or the Steam overlay (Shift + Tab) → friend’s name → Invite to Lobby.
• Invite up to three friends. As they connect they appear in the lobby.
• Everyone picks a character. Duplicates are allowed — four Ironclads is a legal, and occasionally very funny, party.
• Players ready up, the host starts, and the climb begins.

Practical note: settle the character question in chat before you open the lobby. Lobby indecision is where co-op nights go to die, and picking blind means nobody plans around anyone else’s kit.

How to join a friend’s run

Two routes, both trivial once you are friends on Steam.

• Accept the Steam invite. The notification drops you straight into the host’s lobby.
• Use the menu. Multiplayer → Join surfaces lobbies hosted by people on your friends list. Refresh if your friend’s lobby has not appeared yet.

Then pick your character and ready up. If you cannot see the lobby, the cause is almost always one of three things: you are not actually Steam friends, one of you is on the beta branch and the other is not, or the host has not opened the lobby yet.

Shared vs separate: who owns what

This is the part new co-op groups get wrong, and it changes how you evaluate every reward screen.

Yours alone

• Deck — your draw, discard and exhaust piles are private. Your card picks do not remove options from anyone else’s reward screen.
• Energy — each player gets their own energy on their own turn.
• HP — separate bars and separate max HP. You can be knocked out while the rest of the party finishes the fight.
• Gold — individual purses, spent individually at shops.
• Potions — your own slots. Some co-op effects can hand potions to allies, but there is no shared belt.

The party’s

• The map. Everyone is on the same floor at the same node, and pathing is a group decision.
• Encounters. Fights, shops, events and campfires are shared nodes — the party moves together.
• Enemies. Same line-up for everyone, with health pools tuned to party size.
• Turn order. Combat runs on a shared sequence so you can see who acts when.

Relics: the middle case

Relics are the interesting one. They drop as party loot and are then assigned to a specific player, and some are written to affect the whole team rather than the holder. So the reward screen is a genuine group conversation: rewards are shared, ownership is not. Dumping every relic on one player usually feels great for two floors and terrible in Act 3, because the party’s weakest link is what actually kills runs.

Campfires

The party arrives at a campfire together, but each player picks their own action. Resting heals your HP, not the team’s, unless a specific relic or event says otherwise. If one player is at 20% and everyone else is comfortable, that is a rest for them and an upgrade for you — not an argument.

How enemies scale with 2, 3 and 4 players

The headline rule, per IGN’s multiplayer breakdown: the more players there are, the bigger the enemy health pools. Mega Crit has not published exact multipliers, so treat the following as texture rather than maths:

• Duo runs feel closest to solo pacing. Fights are a little longer, mistakes are recoverable.
• Trio and four-player runs are noticeably swingier. Fights last long enough that a bad opening turn compounds, and every player who is not blocking is a target.
• Support and block-heavy decks gain value at higher player counts, because there are simply more allies worth protecting.

Beta patch v0.108.0 also adjusted how enemy modifiers behave in multiplayer — Artifact, Slippery and Skittish were among the properties touched — which changes which debuff-reliant decks feel good in a four-stack.

Co-op-only cards, and what v0.108.0 changed

Multiplayer has its own card pool that never appears in solo runs. These cards are built around interacting with other players: copying cards into an ally’s pile, buffing a teammate’s stats, or triggering off what everyone else draws or exhausts.

The 2 July 2026 beta patch (v0.108.0) added 15 multiplayer cards — three each for Ironclad, Silent, Necrobinder and Defect. The most visible balance change in that batch was to a tank-support effect: the caster now takes +50% damage instead of +100% while allies take 50% less. That is a straight buff to playing designated meat shield, which is exactly the role Ironclad wants in a four-stack given how freely it spends HP.

If your group cares about the multiplayer pool specifically, our breakdown of what Mega Crit’s recent balance patches are actually targeting covers the design direction behind these changes.

Can someone join halfway through?

No. A co-op save is bound to the roster it started with. You cannot begin a solo run and let a friend hop in, and you cannot turn a two-player campaign into a three-player one. To continue an existing co-op save, you re-form the same party.

Disconnects are a different case: a player who drops can reconnect into their own slot, and reconnect handling has been one of the areas patched during 2026. That is recovery, not drop-in co-op.

Things the community still argues about

A couple of details get repeated confidently online that are not documented in Mega Crit’s own materials, so treat them as unverified until a patch note says otherwise: the exact number of save profiles per Steam account, and whether co-op runs on a fully separate Ascension track from solo. Both claims circulate, neither appears in official patch notes. If you are chasing Ascension specifically, our breakdown of every Ascension level, A1 to A10 sticks to what the game actually shows you.

Practical tips for smoother runs

• Assign loose roles in the lobby. Who is tanking, who is scaling, who is picking up utility. It changes how each of you values card rewards from floor one.
• Talk relic assignment out loud. Ten seconds of discussion beats a silent misclick that hands a defensive relic to the player already sitting at full HP.
• Vote paths fast. Long map deliberation is what turns a 60-minute climb into a two-hour one.
• Plan campfires around the weakest player. Upgrades are worthless if someone dies to the next elite.
• Use voice chat. There is no in-game voice, and co-op turns involve reading three other people’s intents. Discord is effectively part of the mode.
• Warn before boss turns. If you like to solve the whole line before playing a card, say so. Nobody minds a pause they expected.

Budget 60–90 minutes for a serious four-player climb. Under-planning the time is the single most common cause of abandoned co-op saves.

FAQ

Is there local or couch co-op?

No. Official co-op is online only. Steam Remote Play can share a screen, but it does not create a real second player with their own deck — everyone needs their own copy and their own connection.

Can I play with strangers?

Not through the game. There is no matchmaking or lobby browser, so you have to add people on Steam first.

Do we all need the same game version?

Yes, in practice. Beta-branch builds like v0.108.0 and v0.109.0 arrive ahead of the main branch, so either the whole group opts into beta or nobody does.

Is co-op harder than solo?

Different rather than strictly harder. Enemy HP scales with party size, so fights last longer and coordination failures cost more, but you also have three other players covering your bad draws and access to a card pool solo never sees.

Which character should I take in co-op?

Whatever your party lacks. Ironclad’s HP-as-a-resource pattern makes it the natural front line, especially after the tank-support buff — our Ironclad guide covers how to build it for the current patch.

The takeaway

Treat co-op as its own mode rather than solo with extra bodies. Host through Multiplayer → Host, invite Steam friends, agree roles before the run rather than during it, and internalise the one rule that governs everything else: the map and the enemies belong to the party, the deck and the HP belong to you. Once that split is instinctive, the rest of Slay the Spire 2 co-op is just the game you already know with three other people making it louder. Its Early Access limits — no consoles, no matchmaking, no drop-in — are real, but none of them stop a fixed group of friends from getting a full campaign out of it. Full game details live on the Slay the Spire 2 hub.