The one rule of lifegain: sources feed payoffs A lifegain deck has two halves, and it is dead without both: Sources cards that gain you life, ideally incrementally and repeatedly (lifelink, whenever a creature enters triggers, upkeep gainers)
Klauths Will Klauth's Will is a hidden gem from Forgotten Realms Commander
Those pesky Simulacrum Synthesizer decks will get what they deserve
Heliod, the Radiant Dawn / Heliod, the Warped Eclipse Heliod, the Radiant Dawn isnt too impressive, so its nice that it wont cost you too much mana to transform it into Heliod, the Warped Eclipse
Archidekt and Moxfield deck URLs can be imported directly into the builder
That leaves us with a relatively small pool of cards to choose best of from, which makes sense for cards that can only be played in such a skewed format