Activate Bartolomé del Presidio by sacrificing Gollum.
When Gollum dies, it and Ratadrabik trigger.
Resolve the Ratadrabik trigger, creating a  nonlegendary token copy of Gollum that is a 2/2 Zombie in addition to its other types.
Resolve the Gollum trigger from step 2, causing the Ring to tempt you, and for the Gollum token to become your Ring-bearer, thus making it legendary.
Resolve the Bartolomé del Presidio ability from step 1, putting a +1/+1 counter on it.
Repeat.

Infinite +1/+1 counters on Bartolomé del Presidio

Infinite death triggers

Infinite ETB

Infinite LTB

Infinite sacrifice triggers

Ratadrabik of Urborg

Gollum, Patient Plotter

Bartolomé del Presidio

Activate Skirge Familiar by discarding Gollum, adding {B}.
Bone Miser's first ability triggers, creating a 2/2 Zombie creature token.
Activate Gollum by paying {B} and sacrificing the Zombie, returning it from your graveyard to your hand.
Repeat.

Infinite self-discard triggers

Bone Miser

Skirge Familiar

Activate Skirge Familiar by discarding Gollum, adding {B}.
Activate Gollum by paying {B} and sacrificing a creature, returning Gollum from your graveyard to your hand.
Tormod triggers, creating a creature token.
Repeat.

Tormod, the Desecrator

Activate Psychic Frog by discarding Gollum.
Activate Gollum by paying {B} and sacrificing a creature, returning Gollum from your graveyard to your hand.
Teval and Kheru Goldkeeper trigger, creating a creature token and a Treasure token.
Activate the Treasure by tapping and sacrificing it, adding {B}.
Repeat.

Infinite +1/+1 counters on Psychic Frog

Kheru Goldkeeper

Psychic Frog

Teval, the Balanced Scale

Activate Mind over Matter by discarding Gollum.
Bone Miser's first ability triggers, creating a 2/2 Zombie creature token.
Resolve the Mind over Matter ability, untapping a mana-producing permanent.
Activate the permanent by tapping it, adding at least {B}.
Activate Gollum by paying {B} and sacrificing the Zombie, returning it from your graveyard to your hand.
Repeat.

Mind Over Matter

Activate a permanent by tapping it, adding at least {B}.
Activate Mind Over Matter by discarding Gollum, untapping the permanent.
Activate Gollum by paying {B} and sacrificing a creature, returning Gollum from your graveyard to your hand.
Tormod triggers, creating a creature token.
Repeat.

Combos with "Gollum, Patient Plotter"