Steal an Egg Rift event: Overlords, Boss Tokens, Mastery, Sacrifices and the three banners

A Rift opens somewhere on the map every 30 minutes. You step inside, fight the Overlord waiting there, and if you defeat it you earn Boss Tokens. Tokens are spent in the Boss Shop. Every Overlord you beat also adds Boss Mastery Points, and the Mastery track unlocks rewards as you progress. That is the whole loop: find the rift, win, spend, repeat on the half-hour.

The Boss Shop sells temporary boosts — cash multipliers, speed multipliers and treadmill boosters — plus one item that is not temporary: a consumable Mutation Shard with a chance to apply a mutation to an egg already sitting in your pen. The wiki's FAQ on the page answers the obvious question: the shard works on both growing and fully grown eggs, and the chance of it working is 10 %.

Read together with the Mutations page, the shard is the only way to add a colour mutation to an egg after the fact; the Mutations page lists Fractured (×2.75) as the mutation that can be applied with a Mutation Consumable at 10 %. So a shard is, in effect, a 10 % ticket to ×2.75 on whatever egg you point it at — which is why the best use is your highest-base egg, not your favourite.

Every Overlord defeated earns Boss Mastery Points, and progressing through the Mastery track unlocks increasingly valuable rewards, including eggs pre-loaded with the Fractured mutation. The wiki does not publish the track's thresholds or the full reward list, so this page does not either. What it does establish is that Mastery is the guaranteed route to a Fractured egg, where the shard is a 10 % route.

Separate from the timed boss fights, a Rift sits permanently in the lobby. It asks for three random pets; hand them over and it grants one exclusive Rift Egg. The catch is which pets it asks for: the Sacrifice draws from whichever banner is currently active, and each banner's pool is split into three difficulty tiers by how demanding the pets are to obtain. The tiers are listed in full below. Rotation is roughly every three hours, and the wiki's FAQ says pity carries over — it does not reset when you leave the game or when the banner changes.

The permanent Rift rotates through three egg pools. Each pool draws its pets from a set of biomes rather than a single zone.

This is the list to check before you commit pets. Easy-tier pets are cheap zone eggs; hard-tier pets are the ones you would rather keep.

Seventeen pets carry the Rift tag in the wiki database (the event page says 18; one may lack an infobox). They span Legendary to Divine and include the two highest-income obtainable pets outside events. None has a listed grow time or hatch reward.

Three things follow from the rules. First, the sacrifice tiers make some cheap pets worth keeping: a Lava Gecko or Parrotfish is easy-tier on two banners, so a pen of them is a Rift Egg waiting to happen. Second, because pity carries over across leaving and rotation, there is no reason to rush a banner you do not like. Third, the 30-minute rift cadence lines up with the five-minute nest reset six times over, so a normal steal-hatch routine fits between rifts without waste.

What the wiki does not tell you, and this page will not guess: how strong the Overlords are, what the Mastery thresholds are, exact Boss Shop prices, or how long the event runs.

Several pets appear in the sacrifice lists of two banners, which makes them the most flexible pets to hold in a pen for the Rift. From the wiki's tier lists:

The seventeen Rift infoboxes break down as one Divine (Shattered Colossus), four Eternals (Void Serpent, Shattered Drake, World Eater, Void Dragon), four Secrets (Shardwing, Mawbreaker, Wendigo, Abyss Overlord), three Cosmics (Shattered Ram, Dreadclaw, Ventinal), three Mythics (Shardling, Riftwing, Voidmaw) and two Legendaries (Void Angler, Rift Eye). Twelve of the seventeen are Secret or above — the Rift is weighted toward the top of the ladder in a way no zone is.

The rift cadence is 30 minutes and the nest cycle is five, so a session naturally splits into six-cycle blocks: steal and hatch on the nest timer, be at the rift on the half-hour, spend tokens, repeat. Because pity carries over across leaving and banner changes, there is no penalty for logging off between rifts, and no reason to force a banner whose tiers ask for pets you would rather keep. Wait roughly three hours for the rotation instead.

The wiki's Rift Event page carries a short FAQ that answers the two questions players ask most. Does applying a Mutation Shard work on eggs that are still growing? Yes — it works on both growing and fully grown eggs in your pen, but there is only a 10 % chance of it working. Does pity reset when I leave or when the banner rotates? No — pity carries over regardless of leaving the game or the banner changing. Those two answers are the whole strategic core of the event: shards are a slow-burn lottery best pointed at your biggest base, and pity means patience costs nothing.

The page headline lists 18 new pets, a Rift Boss Event, Boss Mastery and a new currency. The currency is the Boss Token, spent only in the Boss Shop. The pets are the seventeen with Rift infoboxes plus, presumably, one not yet documented. None of them is a nest pet, which is why the zones page treats the Rift as an event rather than a thirteenth zone, and why the pets hub lists them without grow times: the wiki has none to give.

The wiki does not give an end date. When the Rift closes, the seventeen Rift pets stop entering the game, the Boss Shop stops selling shards, and Fractured becomes obtainable only through whatever the developers add next. If you want a Rift pet, the register's advice reduces to one line: fight the Overlord every 30 minutes while you can, and keep the sacrifice-tier pets in a pen.