These colors have only three non-rare creatures below four mana which both attack for damage and survive Stab (and two are uncommon)
You can add counters to lands, such as Gemstone Mine, you can hit a creature with a -1/-1 counter and make this a minor proliferate, and more
Though Miles Morales is technically a mono-green card, its color identity includes red and white because Ultimate Spider-Man has those colors in its casting cost
There are a lot of sideboard options available to you, but to run through a few I particularly like, I do think Dive Down gets a lot better in sideboarded games if you know your opponent will be dense on removal for Games 2 and 3, so whilst maindecking this card is unappealing I have enjoyed having access to the card in my 75
The cards signature ability Off With Their Heads
But if youre playing any deck that wants to Fling creatures, or give everything trample, or use Mage Slayer, or even just gain a bunch of life off of power, then this is the card for you