Open Arms

Enchantment
At the beginning of each upkeep, if you control no creatures, gain control of target creature of an opponent’s choice they control.

Purebred Stallion

Creature - Horse Mount
Whenever Purebred Stallion attacks while saddled, it gains first strike until end of turn. If it is saddled by a Knight, it gains double strike instead.
Saddle 2 (Tap any number of other creatures you control with total power 2 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)
2/2

Quartering Act
Enchantment - Aura (R)
Enchant opponent
Creature spells you cast cost less for each creature enchanted player controls.
"We'll be taking the main suite, thank you kindly."
—Diln, Ramosian Captain

Reunion of Brothers

Sorcery
Search your library for up to two creature cards with mana value 2 or less, reveal them, put them into your hand, then shuffle. Create two Food tokens. (They’re artifacts with “, , Sacrifice this artifact: You gain 3 life.”)
When Sir Lancel and Sir Brilbury meet you can guarantee three things: war stories, deafening laughter and a very expensive bar tab.

Slayer's Moment

Instant
Target creature gets +1/+0 and gains First Strike and Protection from Vampires, Demons, and Dragons until end of turn.

Teyo's Deliverance

Instant
Distribute three Shield counters among creatures you control. (If it would be dealt damage or destroyed, remove a shield counter from it instead.)
"Triangles are the most stable shape, but also form the most resilient shield."
—Teyo, the Shieldmage

Usher the Dead
Instant
Exile all cards from target player's graveyard. If this spell was foretold, you may choose a creature card with mana value 3 or less exiled this way. Put it onto the battlefield tapped.
Foretell
Valkyries visit in pairs, one to defend the worthiness of the dead the other to prosecute their cowardice. For those special few, the two are in perfect agreement.

Valkyrie of Valor
Creature ─ Angel Warrior ()
Flying
Morbid ─ Foretell
2/2

Is the morbid restricting the foretelling or the casting while foretold?

Will of the Gods
Instant
Shuffle your library, then draw a card and reveal it. If that card has miracle, add . Otherwise, you gain 3 life and scry 3.

I was thinking it would gain the Foretell when a creature died, but I think that means it will lose foretell while exiled and then you can't play it? Or can it be both? A creature dies, it gains Foretell, you pay the foretell cost and now its exiled, but it loses Foretell again until another creature dies? Does that work?

To be technical, morbid means nothing on its own. You have to write out what it does.

If it's worded as "As long as a creature died this turn, this card has foretell ," then yeah, I think a creature has to have died for it to be foretold (exiled from hand face-down). I think it would then also only have a foretell cost (what you'd pay to cast it face-up) if a creature has died, but the wrinkle is it's face-down in exile, so it doesn't really have that ability. Because face-down things can check the other side for a morph/disguise/foretell cost, I think it still works.