Activate The Chain Veil by paying ({4} magic symbol) and tapping it, allowing an extra activation of your planeswalkers' loyalty abilities this turn.
Activate Teferi's first loyalty ability by putting a loyalty counter on it, untapping The Chain Veil and up to other other creature and/or land you control, and causing you to gain 2 life.
Repeat.
Results
Infinite activations of loyalty abilities of all other Planeswalkers you control.
Infinite death triggers.
Infinite ETB.
Infinite lifegain.
Infinite lifegain triggers.
Infinite LTB.
Infinite mana creatures you control can produce.
Infinite mana lands you control can produce.
Infinite mana permanents you control can produce.
Infinite sacrifice triggers.
Infinite untap of lands and creatures you control.