As a rule, it ranges from cheap and narrow effects (Ceremonious Rejection, Negate, Revolutionary Rebuff) to high power with higher costs (Insidious Will, Summary Dismissal, Confirm Suspicions)
You could try to use Town Greeter and dual lands to play all three colors, reaping the best cards and synergies from each
The damage it deals might be minor, but using it too much will put your other cards in the danger zone
Squeezing another two or three instances of lifegain out of your deck on your opponents turns could mean the difference between obliterating them with Aetherflux Reservoir or your imminent defeat
His sentence is always death
That alone is a solid token for 6 mana, but storm turns this into an aerial army that grows bigger with each noncreature spell you cast