The Boss Milestone track in Steal an Egg (the game calls it Boss Mastery) adds one point every time you finish off Dr. Scramble’s Mech, and it stretches all the way to 100 kills. The whole thing is free, and there’s no Robux shortcut. At the very top sits the Eternal Pink Dragon Experiment #010.
Along the way you’ll pick up Eye Bat #021 at 10 kills, Citadel Snail #007 at 25, Uncoiled Armadillo at 50, and a Secret-rarity pet at 75. Because the Mech portal opens roughly every 30 minutes, the full climb works out to about 50 hours of back-to-back fights.
How the 100-Kill Track Actually Works
Every victory over the Dr. Scramble boss gives you exactly one Boss Mastery point. It doesn’t matter how fast you win or how many players joined the fight. One kill, one point.
The track itself has 22 milestones spread across those 100 kills. Most of the early ones are Biohazard, Experiment, and Unstable eggs, plus their Scrambled versions. The named pets only start showing up once you pass the 10-kill mark.
The boss is the same one from the Dr. Scramble’s Revenge update, and if you haven’t cleared him yet, the Mech boss walkthrough covers the phases. This guide only cares about what happens after the final hit lands.
Every Boss Milestone Reward, Kill by Kill
Here’s the track as it currently displays. Milestones marked with a dash are egg rewards whose exact kill counts weren’t clearly visible when we checked.
| Boss kills | Reward | Rarity |
| 1 | Biohazard Egg | Egg |
| 3 | Experiment Egg | Egg |
| 10 | Eye Bat #021 | Legendary |
| 18 | Scrambled Experiment Egg | Egg |
| 21 | Unstable Egg | Egg |
| 25 | Citadel Snail #007 | Mythic |
| 50 | Uncoiled Armadillo | Cosmic |
| 75 | Secret pet (see note below) | Secret |
| 90 | Scrambled Unstable Egg | Egg |
| 100 | Pink Dragon Experiment #010 | Eternal |
| Scrambled Biohazard Egg and other eggs | Egg |
One honest caveat on the 75-kill slot. Different listings name that Secret pet differently, with some showing Mecha Chompa and others showing Toxic Crocodile. We couldn’t confirm which label is correct, so check your own Boss Mastery menu before you plan around it.
Which Milestones Are Actually Worth Stopping For?
Not every tier deserves equal attention, and the gaps between them are uneven.
The 10-kill Eye Bat #021 is the quickest real pet on the track. At two fights an hour, you’re looking at about five hours of portals, which is a single long evening. It’s a Legendary, so it won’t change your income, but it’s a solid early pick-up.
The 25-kill Citadel Snail #007 (Mythic) and the 50-kill Uncoiled Armadillo (Cosmic) are where the grind starts to feel like a commitment. Fifty kills alone is around 25 hours of portals.
The real prize is the top. The Pink Dragon is an Eternal, the same top rarity tier as the Eternal Gorilla King, and it’s reported to generate around $32B/s. That figure comes from a single source, so treat it as unconfirmed until you see it in your own pen.
How Long Does It Really Take to Reach 100 Boss Kills?
The portal timer is fixed, so the math is simple. One fight every 30 minutes means a hard ceiling of two kills per hour, and only if you never miss a spawn.
| Milestone | Kills | Minimum time (non-stop) |
| Eye Bat #021 | 10 | 5 hours |
| Citadel Snail #007 | 25 | 12.5 hours |
| Uncoiled Armadillo | 50 | 25 hours |
| Secret pet | 75 | 37.5 hours |
| Pink Dragon Experiment #010 | 100 | 50 hours |
That’s the theoretical floor, not a realistic schedule. Nobody catches every portal, and fights don’t start the instant the previous one ends. Plan on noticeably longer, spread over several days of play.
Can You Speed Up Boss Mastery Progress?
Sort of, but not by much. Since every kill is worth one point regardless of group size, you can’t farm points faster by bringing friends. What you can do is make each fight shorter and more reliable.
- Never skip a portal. With a fixed timer, every missed window costs you half an hour.
- Bring your strongest bat. A better bat speeds up every phase, which matters most in the overheat windows.
- Fight in a full server if you can. Solo clears are possible, and private servers do spawn the boss, but a crowd makes the core and pylon phase far more forgiving.
- Spend Samples wisely between fights. A solo win pays 1,750 Samples, and the big purchase is Experiment #001.
If you’re also working the Laboratory trade-ins, the eggs you collect from Mastery feed straight into those recipes, so nothing gets wasted.
How Do You Claim Boss Mastery Rewards?
This trips people up more than anything else on the track. Rewards do not arrive automatically after a win. You have to collect them by hand.
- Look for the green test-tube button on the left side of your screen.
- Tap it to open the Boss Mastery menu.
- Press the green Claim button next to any unlocked milestone.
A locked card only shows what the menu displays, not that you’ve received the item. If a milestone looks reached but nothing is in your inventory, you probably just haven’t claimed it yet.
Is the Pink Dragon Experiment #010 Worth 100 Kills?
If you play regularly and the boss is still spawning, yes. It’s free, it’s an Eternal, and there’s no other route to it listed right now. The trade-off is time, not money.
If you only log in for short sessions, the math is harder. Hitting 100 kills needs dozens of portal windows, so prioritize the 10-kill and 25-kill pets first and treat the top prize as a long-term goal rather than a weekend target.
The same kill-counting setup appeared in the earlier Rift event, so if you’ve climbed a boss track before, the rhythm will feel familiar. Just expect this one to be far longer.
What We Couldn’t Confirm Yet
A few details are still unclear, and we’d rather flag them than guess.
- The 75-kill pet name. Listings disagree, as covered above.
- The full 22-milestone list. Only part of the middle of the track has been clearly confirmed.
- How long the track stays available. The official event window was listed as a short one, yet the boss has kept appearing afterward. A teased new biome suggests more changes are coming, so keep an eye on the Steal an Egg updates page.
- The Divine drop rate. Every kill has a very rare chance at the Divine Mecha Scrambler, but no drop rate has been confirmed.
If you’re chasing the top reward, don’t wait. Check your Boss Mastery progress, catch the next portal, and keep the count climbing.