Dictate of Erebos lets you surprise your opponents with the effect, which can be useful when they cast removal targeting your creatures
Usually, its worst-case scenario is as a 4x Extract type of effect/generic draw effect ala Deep Analysis, and it being splashable helps a drafter who takes it early put it in just about any deck
You can pay two mana and unattach Sunforger from a creature to go get a red or white instant card that costs four mana or less, letting you cast it immediately
Finally, Sagas themselves are an increasingly well-supported card type with powerful, interesting commander options like Tom BombadilTom Bombadil, Narci, Fable SingerNarci, Fable Singer, and Sigurd, Jarl of RavensthorpeSigurd, Jarl of Ravensthorpe