Activate Famished Paladin using Soulmender's ability by tapping it, causing you to gain 1 life.
Famished Paladin triggers, untapping itself.
Repeat.

Infinite lifegain

Infinite lifegain triggers

Agatha's Soul Cauldron

Famished Paladin

Soulmender

Activate Lurking Roper using Soulmender's ability by tapping it, causing you to gain 1 life.
Lurking Roper triggers, untapping itself.
Repeat.

Lurking Roper

Activate Soulmender by tapping it, causing you to gain 1 life.
Heliod triggers, putting a +1/+1 counter on Crystalline Crawler.
Activate Crystalline Crawler's first ability by removing a +1/+1 counter from it, adding {U}.
Activate Pemmin's Aura's first ability by paying {U}, untapping Soulmender.
Repeat.

Combos with "Soulmender"