Cast the non-card copy of the spell in exile by paying its mana cost, unpreparing Emeritus of Woe // Demonic Tutor.
When you cast that spell, Spellweaver Helix's last ability triggers, allowing you to cast a copy of the Extra Turn Sorcery without paying its mana cost and take an extra turn after this one.
Resolve the spell from step 1.
Activate Eldrazi Displacer by paying mana, flickering Emeritus of Woe // Demonic Tutor, which enters prepared.
Repeat each turn.

Infinite turns

Lock

Extra Turn Sorcery

Card with same name as prepare spell

Spellweaver Helix

Eldrazi Displacer

Emeritus of Woe // Demonic Tutor

Cast the copy of Demonic Tutor from exile by paying {1}{B}, unpreparing Emeritus of Woe.
When you cast that spell, Spellweaver Helix's last ability triggers, allowing you to cast a copy of the Extra Turn Sorcery without paying its mana cost, causing you to take an extra turn after this one.
Resolve the copy of Demonic Tutor, finding Siege-Gang Lieutenant and putting it into your hand.
Cast Siege-Gang Lieutenant by paying {3}{R}.
At the beginning of combat, Siege-Gang Lieutenant's first ability triggers, creating two 1/1/ red Goblin creature tokens with haste.
Activate Siege-Gang Lieutenant's last ability twice by paying {4} and sacrificing both Goblin tokens, dealing 2 damage to any target.
At the beginning of your end step, Emeritus of Woe triggers, preparing itself.
Repeat each turn, finding any card of your choice in step 4 instead of Siege-Gang Lieutenant.

Demonic Tutor

Siege-Gang Lieutenant

Cast a copy of the prepared spell by paying its mana cost.
When you cast that spell, Displacer Kitten and Dovescape trigger.
Resolve the Dovescape trigger, countering the prepared spell and creating a number of 1/1 flying Bird creature tokens equal to its mana value.
Resolve the Displacer Kitten trigger, blinking Emeritus of Woe // Demonic Tutor, which enters prepared.
Activate Phyrexian Altar by sacrificing a Bird token, adding one mana of any color.
Repeat step 5 until you have enough mana to cast the prepared spell.
Repeat.

Combos with "Emeritus of Woe // Demonic Tutor"