First, we've got Trial // Error, a split card that combined has Esper colors, that is, until you realize it doesn't have the fuse keyword that would let you cast both parts of it
Tamiyo starts out as a superbly cheap creature who can generate card advantage, but if you can draw three cards you get a somewhat slow value engine that can recur instants and sorceries
Well be able to defeat the battle and get our creature going despite hostile countermagic
702.174m: If part of a spells ability has its effect only if its gift was promised, and that part of the ability includes any targets, the spells controller chooses those targets only if the gift was promised.
Leyline of Hope Lifegain payoffs and anthem effects are oversaturated, and not every lifegain deck even cares about pumping its creatures
These cards are "useless" in that they are banned from basically every format