Body Launderer | Felidar Guardian | Mikaeus, the Unhallowed

(and one other card)

Activate
Phyrexian Altar by sacrificing
Felidar Guardian, adding one mana of any color.
When
Felidar Guardian dies, its undying ability and
Body Launderer's first ability trigger.
Resolve the
Body Launderer trigger, causing it to connive.
Resolve the
Felidar Guardian trigger, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
When
Felidar Guardian enters the battlefield, it triggers, targeting
Body Launderer.
Holding priority, activate
Phyrexian Altar by sacrificing
Felidar Guardian, adding one mana of any color.
When
Felidar Guardian dies,
Body Launderer's first ability triggers, causing it to connive.
Resolve the
Felidar Guardian trigger from step 5, blinking
Body Launderer.
Activate
Phyrexian Altar by sacrificing
Body Launderer, adding one mana of any color.
When
Body Launderer dies, its undying and second ability triggers.
Resolve the undying trigger, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
Resolve the second
Body Launderer trigger, returning
Felidar Guardian from your graveyard to the battlefield.
When
Felidar Guardian enters the battlefield, it triggers, blinking any other permanent you control.
Repeat.