Alex, I know it doesn't feel specifically like an enchantment, but you can think about it laying little mini enchantments on creatures each turn.

"That creature is blockable"? That's a curious turn of phrase I've not encountered before.

EDIT: Ah, I see it's as discussed on How can monocolor deal with flying?. Probably worth trying to crosslink discussions where possible, as it's somewhat hard to keep up with current proposals.

I don't think the rules handle it, either. It's meant as the logical opposite of "unblockable." I made a mistake earlier when I said the reminder text for flying uses the word unblockable, but the reminder texts for landwalk and intimidate do. Also, there are creatures that are straight up unblockable.
Basically, this is meant to make landwalk, intimidate, unblockable, flying, etc. "useless" for a turn without all of the extra words. I thought it was easy to grasp, but maybe it isn't as easy as I thought, if you're confused.

I was principally confused because it looks like it could be a typo for "unblockable".

I fear the rules don't like it. The rules have an unnatural preference for prevention ("can't") over enabling ("can"). So "unblockable" works to override something's normal blockability, but "blockable" doesn't override evasion abilities like flying.

The concept is still fine. "can be blocked as though it had no abilities" is how I think it'd need to be phrased in the rules. I wonder whether we could add a keyword for that effect, and whether we'd want to.

Yes, I was just talking that over with my roommate. It doesn't make as much sense as I would like, unfortunately.

Unfortunately, what Alex is talking about is called "The Golden Rule of Magic". I'm pretty sure we can't butt heads with a golden rule.

You could however just say that something is blocked. Or have your creature give another creature ": This creature is blocking target creature".

Changed from "target creature is blockable" to "Until end of turn, creatures you control may block target creature as if they had reach." since that's the reason why this card is doing what it is doing anyway. A bit spot on, but it seems fine to me.

Hmm... how about "That creature loses flying and landwalk UEOT"?

It's too bad "that creature loses all evasion abilities UEOT" doesn't make sense to most people, or the rules.

I like "can be blocked as if it had no abilities" if possible, because it sounds really weird, but is mostly straightforward, and I like that for white in this set. Otherwise, I agree the other possibilities would work, but if blue is full of landwalk it would be nice to have an answer to that as well, but spelling out "flying and landwalk" is a bit clunky.

Temporarily changed it Jack's suggestion because I like how funky that is. Unfortunately, it probably isn't common, since I don't know if new players would understand what that means. Would be interesting to test this card with some new players to see if they grok it immediately, though.

I do love the ability. As it happens it's another ability that was in Verdia: there was a rare Giant who could "block creatures as though they had no abilities". It was a very cool idea to see at rare. It's plausible at common, because it is so naturally comprehensible, but I agree I'd want to try it.

Had a chance to test Mono-White v. U/B/R today. It seems that, at least in white, having a non-flying color play against a flying color was plenty of twist turns and switcheroos. In fact, there seemed like more interaction was going on in this matchup then in many past draft matchups where all-flying decks would pop up (Birds in Onslaught, or Fairies in Lorwyn, for example).

Of all the cards in White, though, this buster put down the kibosh, holding back whole armies. I'm rather impressed by this Crossbow Infantry. I didn't see it turning MVP in the right matchups, but it's clearly clutch in block.

Yeah, I was always very happy to draw this when I was playing white. It's naturally defensive, but it's a heck of a defender. The big strike against it (which I think is keeping it reasonable) is that to block anything with more than 1 toughness, it needs you to leave two creatures back - this and another creature to do the actual blocking.

Oh, glad this went well!

Moved to uncommon as per suggestions on How can monocolor deal with flying?. Evidently we have too many answers in White? Go figure.

I suppose that means we have a hole to fill in white common creature. Something with a casting cost of 3 would be preferable... otherwise, there's probably some shufflin' to do.