There are so many things that Ash Blossom & Joyous Spring hits, making it such a good staple
The strategy consists in the "Danger!" monsters revealing themselves in their owner's hand to activate their effects, then "hiding" in the hand again, making the opponent randomly discard a card from their opponent's hand
A creature that gets -1/-1 won't get an additional -2/-2 if it later becomes green and/or white
This keeps them on the back-foot and dancing to your tune until you're ready to deploy characters with 'Evasive' (meaning they can't be challenged unless the other card has Evasive too)
This is, perhaps surprisingly, a new archetype for mono-white in EDH, where Voltron strategies have largely been aura and equipment based, all the way back to Sram, Senior Edificer
As mentioned earlier, Cyclonic Rift is a superb card and getting a slightly nerfed version for free is beyond good