While some split cards let you cast one or both sides in the same turn, there are split cards with an aftermath mechanic where you cast one side, wait for the card to hit the graveyard, then cast the aftermath portion
Still, its powerful, capable of outputting 180 damage with Super Splash or delivering 100 damage to every Pokmon on the opponents bench with Towering Splash-GX
With 180 HP, it wont be knocked out any time soon
Sure, you wont be able to get more than an Amass 1 off a Proliferate (since its real difficult to have multiple zombie armies), so theres a low ceiling on the benefit
Of course, you can just use basics or play with dual lands that come in tapped, but in a world where the best builds are shared online, anyone making that choice knows full well that their deck is fundamentally worse than their opponents'
Itll help you get access to the cards you want that you discarded, or your opponents may just let you keep swinging or not attack to prevent Toluz from dying