Infinite creature ETBInfinite creature tokensInfinite untap of creatures you controlInfinite mana creatures you control can produceInfinite magecraft triggersInfinite landfall triggersInfinite copies of all permanents
How it works
Cast Doppelgang by paying 6, targeting Breaching Hippocamp and a mana-producing permanent.
Holding priority, activate Echo Mage by paying and tapping it, copying Doppelgang, targeting Breaching Hippocamp and a mana-producing permanent.
Resolve the copy of Doppelgang, creating two copies of Breaching Hippocamp and the mana-producing permanent.
When the Breaching Hippocamp tokens enter, they trigger, untapping Echo Mage and any other applicable permanent.
Holding priority, activate the two mana-producing permanent tokens by tapping them, adding at least .