Cast Rot Hulk by paying {5}{B}{B}.
Rot Hulk dies as a state-based action due to having zero toughness.
Rot Hulk's enter the battlefield trigger is put onto the stack.
Resolve the Rot Hulk trigger, returning Rot Hulk and Infectious Host from your graveyard to the battlefield.
Rot Hulk and Infectious Host die as a state-based action due to having zero toughness.
The Infectious Host and Rot Hulk triggers are put on the stack.
Resolve the Infectious Host trigger, causing target player to lose 2 life.
Repeat from step 4.

Infinite death triggers

Infinite creature ETB

Infinite lifeloss

Infinite creature LTB

Rot Hulk

Godhead of Awe

Engineered Plague

Infectious Host

Cast Rot Hulk by paying {3}{B}{B}.
Rot Hulk dies as a state-based action due to having zero toughness.
Rot Hulk's enter the battlefield trigger is put onto the stack.
Resolve the Rot Hulk trigger, returning Rot Hulk and Infectious Host from your graveyard to the battlefield.
Rot Hulk and Infectious Host die as a state-based action due to having zero toughness.
The Infectious Host and Rot Hulk triggers are put on the stack.
Resolve the Infectious Host trigger, causing target player to lose 2 life.
Repeat from step 4.

Combos with "Infectious Host"