I agree. A druid that could Wild Shape into an enormous ice breathing wolf would be overpowered. 

It's lore thing, it's beast made/bred by giants and enhanced by magic. Their are some beast that on the edge of beast/monstrosity like the giant eagle (much smarter then norm, bigger, and have a "language" though they don't really use words). Winter wolves, were artificially made, they are very intelligent, and are magical, so they are monstrosities.

You can't really tame a creature that's as smart as some people and can speak an actual language, you befriend it 

I really like it, I'm just sad that its evil

Instead of being exclusively linked to evil giant, you could have unaligned ones in the wilds.

Or be linked to the sole concept of winter : having Evil ones in service of Auril in the Forgetten Realms, or Lawful Neutral in service of the Raven Queen (who has the winter domain in both the dawn war pantheon and the exandrian one).

are you able to tame one of these?

This monster is tough to beat for beginners and for level five apparently. A character in my campaign just died from one. Don't underestimate any monsters!!!!

How did this eventually play out?

how many of these are in a pack?

Up to the DM.

Do they have to be evil?

The Baby Bestiary handbooks (vol 1 & 2) contain rules about taming monsters. The Winter Wolf isn't in the books but it's a good guideline.

P-S: Sorry for my poor english, I am french

It could be a funny gag. A northman barbarian who only knows common and seeming gibberish. Then later on a random encounter with these guys happens and they finally get to use their high charisma. 

They make for really cool mounts

If you're looking for an early-game boss that your party can get a fair reward from, look no further. It's got HP to hack away at, enough INT to get the RP juices flowin' if you're into that, it looks rare enough to give your party some sizable coin for bringing down, and its cold breath is a great early-game teacher for what things are dangerous. Additionally, even in mid or late game, you could have a village of Frost Giants that tames these guys, which can be a real threat with their Pack Tactics and ranged support from rock throwing Giants. They're an all-around great monster, and remain a sizable threat throughout the entire game. Solid.

"Monstrosity" - "Wolf".  Sigh, this would have been a cool animal to combat Wildshape into.  Hopefully my DM would allow it anyways.

Ice shaper frost giants can summons 4 of these bad bois but as elementals instead of monstrosities. yikes!

I sure do wish my character could learn how to speak “Winter Wolf”

i acthully got a pet baby winter wolf

Missed opportunity to call the Cold Breath a "Howling Wind', lol.