You have an amount of mana available equal to three minus the number of +1/+1 counters on
Runaway Steam-Kin.
Steps
If
Runaway Steam-Kin has three or more +1/+1 counters on it, activate
Runaway Steam-Kin by removing three +1/+1 counters from it, adding ({R} magic symbol) ({R} magic symbol) ({R} magic symbol) .
Activate
Cormela by paying ({1} magic symbol) and tapping it, adding ({U} magic symbol) ({B} magic symbol) ({R} magic symbol) that can only be spent to cast instant and/or sorcery spells.
Cast
Twinflame by paying ({1} magic symbol) ({R} magic symbol) .
Runaway Steam-Kin triggers, putting a +1/+1 counter on itself.
Resolve
Twinflame, creating a token copy of
Cormela.
Put the tapped
Cormela into your graveyard due to the legend rule.
Cormela dies, triggering itself, returning
Twinflame from your graveyard to your hand.
Repeat.
Results
Infinite black mana that can only be spent to cast instant and sorcery spells.
Infinite blue mana that can only be spent to cast instant and sorcery spells.