You control a creature and/or a land that can tap to produce at least ({5} magic symbol) .
You control at least four creatures.
Steps
Activate Teferi's first loyalty ability by putting a loyalty counter on it, untapping The Chain Veil and the creature and/or land that can produce at least ({5} magic symbol) , and causing you to gain two life.
Activate the creature and/or land by tapping it, adding at least ({5} magic symbol) .
Activate The Chain Veil by paying ({4} magic symbol) and tapping it, allowing each Planeswalker to activate their loyalty abilities an extra time this turn.
Repeat.
Activate Xenagos' first loyalty ability by putting a loyalty counter on it, adding ({R} magic symbol) or ({G} magic symbol) for each creature you control.
Activate The Chain Veil by paying ({4} magic symbol) and tapping it, allowing you an additional activation of each of your planeswalkers this turn.
Activate Teferi's first loyalty ability by putting a loyalty counter on it, untapping The Chain Veil and up to one other creature or land you control, and causing you to gain 2 life.
Repeat.
Notes
If you control five or more creatures, this combo will net infinite mana, and you may then activate any of Xenagos' other abilities. You may also tap any other creature and/or land to reduce this cost and/or gain more mana, and untap them via Teferi.
Results
Infinite ETB.
Infinite lifegain triggers.
Infinite lifegain.
Infinite red mana.
Infinite creature tokens.
Infinite mana lands you control can produce.
Infinite green mana.
Put all creature cards from your library onto the battlefield.
Infinite untap of creatures you control.
Infinite mana creatures you control can produce.
Near-infinite landfall triggers.
Exile your library.
Infinite mana permanents you control can produce.
Infinite untap of lands you control.
Infinite activations of loyalty abilities of all other Planeswalkers you control.
Put all land cards from your library onto the battlefield.