Reiterate + Seething Song + Runaway Steam-Kin + Ruby Medallion

Reiterate

Seething Song

Runaway Steam-Kin

Ruby Medallion

How it works

1. Cast Seething Song.
2. In response, cast Reiterate, targeting Seething Song and paying the buyback cost.
3. After Reiterate and the copy of Seething Song resolve, cast Reiterate targeting Seething Song and paying the buyback cost.
4. Remove three +1+1 counters from Runaway Steam-Kin to produce .
5. Repeat the loop from step 3, removing counters from Runaway Steam-Kin for mana every three iterations.