Infinite creature ETBInfinite creature LTBInfinite +1/+1 counters on creatures you control
How it works
Cast Yannik either from your hand or from the command zone by paying 2 plus commander tax, if applicable.
Yannik enters the battlefield, exiling Felidar Guardian and putting a +1/+1 counter on any other creature you control.
Cast Lumbering Battlement by paying 4.
Lumbering Battlement enters the battlefield, exiling Yannik.
Yannik leaves the battlefield, returning Felidar Guardian from exile to the battlefield.
Felidar Guardian enters the battlefield, blinking Lumbering Battlement.
Lumbering Battlement leaves and enters the battlefield, returning Yannik from exile to the battlefield, and triggering Lumbering Battlement's enters-the-battlefield ability.
Yannik enters the battlefield, exiling Felidar Guardian and putting a +1/+1 counter on any other creature you control.
Resolve the Lumbering Battlement trigger, exiling Yannik.