Cast Nissa by paying {5}{G}{G}.
The Sixth Doctor triggers, copying the Nissa spell, with the copy being nonlegendary.
Resolve both Nissa spells.
Activate a mana-producing land or creature by tapping it, adding at least {1}.
Activate Romana II by paying {1} and tapping it, creating a copy of the Nissa token.
Activate a Nissa token's first loyalty ability by putting two loyalty counters on it, untapping Romana II, up to one other creature and up to two lands.
Repeat from step 4.

Infinite mana lands you control can produce

Infinite mana creatures you control can produce

Infinite untap of lands you control

Infinite untap of creatures you control

The Sixth Doctor

Romana II

Nissa, Genesis Mage

Activate two creatures and two lands by tapping them, adding at least {5}.
Activate Nissa's first loyalty ability by putting two loyalty counters on it, untapping those creatuers and lands.
Activate Emiel the Blessed by paying {3}, blinking Nissa.
Activate Luxior's first equip ability by paying {1}, attaching it to Nissa.
Repeat.
Once you have infinite mana, you may repeat but activate Nissa's second loyalty ability instead in step 2, and you may activate Emiel any number of times.

Infinite blinking of creatures and planeswalkers

Infinite LTB

Infinitely large creatures until end of turn

Infinite mana creatures and lands you control can produce

Infinite planeswalker activations

Luxior, Giada's Gift

Emiel the Blessed

Activate Avid Reclaimer by tapping it, adding {U} and causing you to gain 2 life.
Activate Pemmin's Aura's first ability by paying {U}, untapping Avid Reclaimer.
Repeat.

Infinite lifegain

Infinite lifegain triggers

Avid Reclaimer

Pemmin's Aura

Activate two creatures and two lands by tapping them, adding at least {4}{C}.
Activate Nissa's first loyalty ability by putting two loyalty counters on it, untapping those creatures and lands.
Activate Eldrazi Displacer by paying {2}{C}, blinking Nissa.
Activate Luxior's first equip ability by paying {1}, attaching it to Nissa.
Repeat.
Once you have infinite mana, you may repeat but activate Nissa's second loyalty ability instead in step 2, and you may activate Eldrazi Displacer any number of times.

Eldrazi Displacer

Combos with "Nissa, Genesis Mage"