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)
You can simply choose cards to rent via the Cardhoarder link on MTGGoldfish decks
Here, the gods are much more human than their Theros counterparts, walking amongst the mortals and lacking indestructibility
Plus its inherited effect gains memory, giving you a greater offensive advantage in battle
That extra ten dollars will also do some extra special good
Or cards that prevent you from losing the game, either straight-up like Stunning Reversal or by ending the turn before Phage's trigger can resolve with Sundial of the Infinite