Because Sandwurm Convergence prevents creatures with flying from attacking you, and Form of the Dragon prevents creatures without flying from attacking you, no creatures can attack you.

You can't be attacked

Lock

Form of the Dragon

Sandwurm Convergence

At the beginning of the end step prior to your turn, Form of the Dragon's second ability triggers, causing your life total to become five.
At the beginning of your upkeep, Axis of Mortality and Form of the Dragon's first abilities trigger.
Resolve the Axis of Mortality trigger, causing you and an opponent to swap life totals.
Resolve the Form of the Dragon trigger, dealing five damage to the opponent who you swapped life totals with.
The opponent loses the game due to having zero life.
You may repeat this during each of your turns.

Target player loses the game on each of your turns

Target opponent loses the game

Axis of Mortality

Archetype of Imagination causes your opponent' creatures to lose flying and be unable to gain flying.
Form of the Dragon prevents non-flying creatures from attacking you, and since none of your opponent' creatures can have flying, no creatures can attack you.

Archetype of Imagination

At the beginning of the end step prior to your turn, Form of the Dragon's second ability triggers, causing your life total to become five.
At the beginning of your upkeep, Form of the Dragon's first ability triggers.
Holding priority, activate Soul Conduit by paying {6} and tapping it, causing you and an opponent to swap life totals.
Resolve the Form of the Dragon trigger, dealing five damage to the opponent who you swapped life totals with.
The opponent loses the game due to having zero life.
You may repeat this during each of your turns.

Soul Conduit

Gravity Sphere causes all creatures to lose flying.
Form of the Dragon prevents non-flying creatures from attacking you, and since no creatures can have flying, no creatures can attack you.

Gravity Sphere

Mystic Decree causes all creatures to lose flying.
Form of the Dragon prevents non-flying creatures from attacking you, and since none of your opponent' creatures can have flying, no creatures can attack you.

Mystic Decree

Delare Anrakyr the Traveller as an attacker.
Anrakyr the Traveller triggers, allowing you to cast Second Chance by paying 3 life.
At the end of your turn, your life total becomes 5.
At the beginning of your next upkeep, Second Chance triggers, causing you to sacrifice it and take an extra turn after this one.
Repeat.

Combos with "Form of the Dragon"