During your precombat main phase, activate Famished Paladin using Temple Elder'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

Temple Elder

During your precombat main phase, activate Lurking Roper using Temple Elder's ability by tapping it, causing you to gain 1 life.
Lurking Roper triggers, untapping itself.
Repeat.

Lurking Roper

Activate Temple Elder by tapping it, causing you to gain life.
The Destined White Mage triggers, putting a +1/+1 counter on Crystalline Crawler.
Activate Crystalline Crawler ability by removing a +1/+1 counter from it, adding {U}.
Activate Pemmin's Aura's ability by paying {U}, untapping Temple Elder.
Repeat.

Combos with "Temple Elder"