Infinite Guideline Station + Time Sieve + The Mind Stone

Decks

How it works

Cast Infinite Guideline Station either from your hand or from the command zone by paying plus commander tax if applicable.
When Infinite Guideline Station enters, it triggers, creating a 2/2 Robot artifact creature token for each multicolored permanent you control.
Activate Infinite Guideline Station's station ability by tapping any number of creatures with total power 12 or greater, putting at least twelve charge counters on Infinite Guideline Station, causing it to become a creature.
Activate Time Sieve by tapping it and sacrificing five Robots, causing you to take an extra turn after this one.
At the beginning of your end step, The Mind Stone triggers, blinking Infinite Guideline Station.
When Infinite Guideline Station enters, it triggers, creating a 2/2 Robot artifact creature token for each multicolored permanent you control.
Repeat from step 3 each turn.

In which brackets is this combo allowed, per Spellbook's Ruthless tier?

1–2 · Exhibition & Core

Spellbook classifies this as Ruthless — not for these brackets.

3 · Upgraded

Spellbook classifies this as Ruthless — not for these brackets.

4–5 · Optimized & cEDH

All combos are allowed.