To determine the total cost of a spell, start with the mana cost or alternative cost (such as a miracle cost) you're paying, add any cost increases, then apply any cost reductions
Babycakes gives us two ways to go, depending on the battlefield state
The second type of cards you can play during the Main Phase are Tamer cards
It doesnt have many applications outside of EDH unless you wanted to get really spicy with Sorin, Imperious Bloodlord in Timeless, but in EDH it chews away at your opponents resources with a few clones
For example, say you airbend, waterbend, and earthbend, then play Avatar Aang
The place where this sees most play is in affinity where it pumps the most things and is vast from very early in the game