({4} magic symbol) available in at least three different colors available.
Steps
Cast
Crystalline Crawler by paying ({4} magic symbol) , ensuring to spend at least three different colors of mana to cast it, causing
Crystalline Crawler to enter the battlefield with at least three +1/+1 counters on it.
When
Crystalline Crawler enters the battlefield,
Railway Brawler triggers, putting four +1/+1 counters on it.
Activate
Crystalline Crawler's first ability by removing all +1/+1 counters from it, adding ({G} magic symbol) ({W} magic symbol) ({U} magic symbol) ({B} magic symbol) and the remaining mana in any combination of color(s).
Activate
Temur Sabertooth by paying ({1} magic symbol) ({G} magic symbol) , returning
Crystalline Crawler to your hand from the battlefield.
Repeat.
Results
Infinite colored mana.
Infinite ETB.
Infinite LTB.
Infinite storm count.
Infinite blinking.
Metadata
In 10 decks according to EDHREC.
Bracket Tag
This combo has been estimated to be Exhibition (Bracket 1+).