Suleiman's Legacy, like several nominees and winners from past sets, hoses bad cards, but does it really well. Being able to combine it with cards that change creature types makes me wary though. Like Thought Lash, it's a lousy card that has too much potential for me to be comfortable calling it "worst" in a set. Corrosion, on the other hand, does a really crappy job of hosing good cards. But it can still do its job, especially if you have mana to spare, and sometimes you do. Snake Basket is actually a pretty good card, albeit one in a pretty specific niche.
Time and Tide is incredibly situational. If you got it where your opponent's creatures all phased out while yours phased in, then it would be quite powerful. But setting that up would be next to impossible. Even if every creature in your deck has phasing, you might still never have a reason to cast Time and Tide. To make it useful, you'd probably be needing a drawn out game of your phasing-based deck against an opponent's phasing-based deck in order to get a moment where Time and Tide would be an effective spell to cast. And when was the last time you piloted a phasing deck against a phasing deck? Yeah, that's what I thought.