Capped at 1 x

It's hard, but possible.  A mini guide:

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1. The penultimate milestone turns green before it's unlocked.  However, it's only functional if your best transcendence time hits 8 seconds.  This is difficult to unlock and requires both mild token grinding and fast reaction times. You'll have to plan your move sequence and execute them in under 8 seconds.  Don't rely on force transcendence: It's too slow.
2. At this point, you need to drop your transcend time down to ~2.03 seconds real time.  Getting below 1.6seconds is doable, but unnecessary:
   1. Reach 1 rebirth points.
   2. Click the challenge button
   3. Hold the enter key down (for all of steps d,e,f,g).
   4. (Get Ready!) Click the transcend button
   5. (Fast!) Click the challenge 2 button
   6. (Fast!) Click the reset for .1 rebirth points button (note: while clicked, it will say you can't rebirth, because enter key is clicking it faster than it refreshing)
   7. (Timing!) Click the reset for transcendent points button as soon as it appears.  Watch your rebirth points and click immediately after they hit 1.0
3. Grind rebirth power or transcend points for your final token(s).  After completing these steps, my tokens cost 853993^-1 transcend point, 5.380e9 rebirth point, and 1.91 best transcendent time.
4. Optional Repeat step 2 a few more times.  If you didn't do so in step 2, try to get your time below 1.6s .  This will make the final milestone more efficient.
5. Earn 1.0 rebirth points but do NOT transcend.  This will activate the final milestone.
6. Wait until you hit 1.0 transcend points
   1. While you're waiting, make sure to max out Rebirth Loop in the hyper energy settings.  You'll want to be buying time tokens while you wait to speed this phase up.