An un-keyworded version of skulk appeared as the first level of the Ring Tempts You mechanic from the Lord of the Rings Magic set
Like, if something was an awesome idea, we did it. He pointed to having a card that showed off 15 different versions of the character Cid, or having just one pair of cards with the Meld mechanic because it mechanically and emotionally fit the characters on those cards as examples
Any effects that last "until your next turn" or similar won't expire just because they'll go through an additional beginning phase
Gitaxian Probe + Mishra's Bauble Let's put it this way: A cantrip that you can pay for with life rather than mana, and tells you what your foe's up to, is so fundamentally broken that Gitaxian Probe is banned in Modern and Legacy, and it's also restricted in Vintage, where it's no stranger to top-tier decks
It takes advantage of those smallball Eldrazi tokens youll be creating, but it also serves as a potential 5-color experience counter commander, if thats something youve wanted
The format has sped up a lot over the past two decades, and there are plenty of great noncreature cards that cost less than four mana, but I'd also miss out on a lot of cards that are well worth running