When Sunken Grave enters, create a tapped 2/2 black Zombie creature token. {5}, {T}, Sacrifice Sunken Grave: Create a tapped 2/2 black Zombie creature token.
Sunken Homestead enters tapped. {T}: Add {B}. {2}{B}: Until end of turn, Sunken Homestead becomes a 2/2 Zombie creature with “When this creature dies, return it to the battlefield.” Activate only if you're horrific.
Sunlit Fissure enters tapped. {T}: Add {G} or {W}. {2}{G}{W}: Until end of turn, Sunlit Fissure becomes a 3/5 green and white Elemental creature with with vigilance and “Whenever this creature attacks or blocks, torment yourself.” It's still a land. (To torment yourself, lose 3 life unless you discard a card or sacrifice a nonland permanent.)
As Sunlit Highland enters, you may pay 2 life. If you don't, Sunlit Highland enters tapped. {T}, Sacrifice Sunlit Highland: Search your library for a Mountain or Plains card, put it onto the battlefield, then shuffle.
Sunrazed Ruins enters tapped. {T}: Add {W}. {2/W}{2/W}: Sunrazed Ruins becomes a 2/3 white Elemental creature with lifelink until end of turn. It's still a land.
Sunswept Grange enters tapped. When it enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.) {T}: Add {R} or {W}.
At day, a welcome retreat. At night, a ritual ground.
{T}, Pay 1 life: Add {R}. {T}, Pay 1 life, Sacrifice Sunwashed Spires: Search your library for a Mountain card, put it onto the battlefield tapped, then shuffle.