Should maybe cost just instead.

I like the card, it's a cool effect. is probably better cost because it's restricted to being a reactive spell, but I didn't think too much about it being {1U}. Some cards have to be stronger or weaker than others. Up to you.

Yeah, this is a cool take on a blue ability that I'm not sure I've seen before.

I removed the nonland 'cause of text space issues. Does that change push it over the limit?

Messing with lands like this can have a Time Walk effect. And that alone isn't necessarily a problem, but it can really screw someone over.

In limited, you spend a lot of time playing around commons. This isn't a healthy common to play around with how it affects lands. You could move it up to Uncommon to get around this, or just have it affect nonland permanents (that's my vote). That will get the enchantments too, which might be what you're aiming for.

Remember: land restriction is a very unfun mechanic.

Actually on second thought, with the preventing-untap the next turn as well, this is totally a Time Walk. This card would see play in Vintage.

You need to add nonland at this mana cost, irregardless of rarity.

Personally, I'd add "nonland" and remove "though long it seem" from the flavor text. That should solve space issues.

With it affecting lands, there might be some play confusion regarding when to cast this for new players (since land drops can't be responded to), so it might just be better to say nonland. Saving a word/line of text on a card isn't worth the time it takes to explain to new players when they should cast this if they want to lock you out of lands. One other point of counterintuitive-ness is that, if you only have one land in hand and your opponent casts this during his or her upkeep, it might just be better to wait until your next turn to play the land, so you're only locked out of the mana for one turn instead of two.

"Whey". ;)

This stops only the untap of permanents that entered the battlefield during a certain turn, so this is not Time Walk unless Unsummon is, or Silence - a card that can undo/prevent a turn's worth of development.

The issue is obviously the non-standard wording "when they do".

That would be a separate paragraph like "Whenever a permanent enters the battlefield this turn, it doesn't untap during its controller's next untap step.", maybe?

Okay, so I added the 'nonland' clause back. Removing some snippets of the flavor text wouldn't help. Actually, adding more of it would enable fitting the text into three lines (in the MSE render). It's somewhat of a hack though, so I this is pretty close to being red flagged for text length if not for anything else.

"When it does" is something that appears in the reminder texts of hideaway cards (Mosswort Bridge and friends) so I don't think "when they do" would be that much of a stretch. Everyone knows what it means, so there is no issue there really.