There and Back Again has exactly two lore counters on it.
Umbral Mantle attached to Satsuki.
Satsuki does not have summoning sickness.
({1} magic symbol) ({BP} magic symbol) , plus an additional ({4} magic symbol) ({BP} magic symbol) available if you do not control a Smaug token available.
Steps
Activate Satsuki by tapping it, putting a lore counter on There and Back Again.
There and Back Again's third chapter ability triggers.
Holding priority, activate Hex Parasite by paying ({1} magic symbol) ({BP} magic symbol) , removing a lore counter from There and Back Again and giving Hex Parasite +1/+0 until end of turn.
Resolve the There and Back Again ability, creating a legendary 6/6 Smaug creature token.
If you control two Smaugs, put one into your graveyard due to the legend rule.
If you do, the Smaug that died triggers, creating fourteen Treasure tokens.
If you made Treasures this way, activate five Treasures by tapping and sacrificing them, adding ({4} magic symbol) ({B} magic symbol) .
Activate Satsuki by paying ({3} magic symbol) and untapping it, giving it +2/+2 until end of turn.
Repeat.
Results
Infinite colored mana.
Infinite death triggers.
Infinite ETB.
Infinite LTB.
Infinitely large Satsuki until end of turn.
Infinitely powerful Hex Parasite until end of turn.
Infinite Treasure tokens.
Infinite untap of nontoken creatures you control.
Infinite mana nontoken creatures you control can produce.