Kozileks Unsealing provides a payoff for that process, restocking your hand after casting a card with high mana value, as well as generating sacrifice-based sources of mana while building up to those big casts
You are guaranteed a card that is graded 8 or higher
Lathil, Blade of the Elves rose to prominence in Commander not just because of building large board states, but its activated ability to end games with massive life loss
This is basically an Augur of Bolas with a cute extra ability that sometimes matters
The deck can reliably cast it on turn two or three, and once resolved, its difficult for your opponent to deal with it due to its Ward 4 ability and the fact that it can close out the game in two or three attacks
Also, they work well together like Lovestruck Beast