The River Heralds will get Explorers of the Deep, which will be built around +1/+1 counters and lands, while the Sun Empire deck will be Veloci-Ramp-Tor, which will play extra lands and play big dinosaurs
At the beginning of your end step, create a 5/5 black Demon creature token with flying, then mill two cards
This is just as much a Commander ramp staple as Sol Ring, except this mana rock can fix your colors as early as turn 2
You can also choose a player thats low on life and force them to give you cards if you're playing an aggressive deck
Any aristocrats deck loves this, and a bunch of tokens decks do too
From strong power boosts to defensive plays, the best leader abilities can impact the board immediately upon activation