The Prestige Multiplier, unlocked after your first clear of the No More Cubes challenge, builds up over time and is set whenever the player prestiges. During the later stages of the game due to its logarithmic scaling this multiplier will require a heavy time investment in order to reach its maximum value.

Time Multiplier: $T=\min\left(S\cdot\left(5.6\cdot10^{-5}\right),63\right)$

S = Time in seconds since this rebirth started.

This value caps at effectiveness when 1,125,000 seconds have passed. As the value of T can never exceed 63. This is roughly 13 days for a single prestige to max out the effectiveness of the time multiplier.

Prestige Multiplier after Prestige: $\left(\log\left(M\right)\cdot4\right)\cdot T$

M = Max Damage Dealt.

T = Time Multiplier.

Convert in game clock to seconds: $f\left(d,h,m,s\right)=86400d+3600h+60m+s$

d = days

h = hours

m = minutes

s = seconds

Tips

To maximize the time multiplier of the prestige multiplier its possible to restart without needing to trigger a prestige. Optimally 300 Challenges could be completed (With an emphasis on leaving 5 Broken Meter challenges). By starting the broken meter challenge and quitting it will set you back to Tier 1 Phase 1 without triggering a prestige (This works with any challenge, it's just that Broken Meter was deduced to be the most worthless). This means the time will continue to build up until you are ready to spend your skill points on new nodes in your tree increasing the effectiveness of the time multiplier. Do note that as soon as all the challenges are completed, this method becomes impossible to do.

Due to the logarithmic scaling of the prestige multiplier in order to see any significant change a multiple of 10 should be aimed for before a prestige. Maximum damage will have a lower and lower impact on this as the difference between 1e100 and 1e200 is only 2x.