This is another combo that produces infinite storm. It does not produce infinite mana, which is something to be acutely aware of.

While Birgi, God of Storytelling is already a great storm-pickup, and Runaway Steam-Kin is a house in the red aggro deck, Grinning Ignus's existence in the cube is for the Ignus combo. The general idea of the combo is that an Ignus on the battlefield can activate its ability and be re-cast if an extra mana is generated during the process. If it's possible to generate the extra mana, Ignus can be cast and returned ad infinitum.

Runaway Steam-Kin may require a little extra mana to get going, since it can only generate the extra mana if it has triggered for three red spells. Once it has enough counters to activate once, it can use the next three Ignus casts to restore the counters and repeat the process.