Even comparatively terrible three-cost ramp spells, like the Ravnican Lockets, have more utility late-game than your average Signet, and thats not counting all the actually unique options available to you
One Union Arena Attack on Titian UA12BT Japanese Booster Box
Sword of Truth and Justice When equipped to a creature, Sword of Truth and Justice gives that card +2/+2 and protection from white and blue
At this point, you have one chance to select a card that you will get to keep
Cooperative gameplay with your own deck means minimal 'quarterbacking' by other players, the deckbuilding feels like its there, but not something you're required to be amazing at in order to enjoy it, and the difficulty settings do a good job of fine tuning what level you want to play at
You can only use each effect of "Phantasos, the Dream Mirror Friend" once per turn