Quote Originally Posted by Dhavaer View Post
Unkicked it is strictly worse than Blazing Volley, which seems fair given the flexibility.

On multicolour cards a pip of the secondary colour can replace the second pip of the primary colour for an effect that would usually require two; for example, Psychic Strike is a hard, unconditional counter for 1UB, which mono-Blue would require UU for.
I went looking and indeed found two more hard counterspells that are exceptions from the UU requirement; Dromar's Charm (WUB) and Fall of the Gavel (3WU). I'd be careful using them as clear indicators since the more recent Temur Charm (URG) only has Mana Leak on it (and there are plenty of things charms have done that are discouraged these days, like Esper Charm's instant speed discard), and there are far more multicolored hard counters that do require UU. I'll certainly concede Fall of the Gavel and Psychic Strike, though - it seems the Azorius and Dimir guilds can channel their non-blue colors to produce effects that fit the flavor of the Guild as a whole.

As for mass creature destruction, the only exception of sorts I've found is Magister of Worth at 4BW; it's easier to argue that Black or White can stand in for the other color for this effect since those are the colors that could do it on their own. (It's also, however, a card designed for Conspiracy, a multiplayer format - where it doesn't have unconditional mass creature destruction.)

An example worth discussing is Terminate (BR), in which replacing the second Black pip of Murder is not only possible, it's paired with a reduction in CMC and a bonus "no regeneration" effect. But then, unconditional creature removal in Black isn't as much of a BB thing as hard counters is a UU thing, as seen in Dominaria's Eviscerate.

I'll concede that it's not impossible for a card to have unconditional mass creature removal without either WW, BB, WB or {W/B}{W/B} involved, but I'd classify it as at least highly unlikely. Mass creature removal is just a much rarer and much more powerful effect than hard counterspells.