What do the Frozen Champions do? Hard to evaluate without that info. Decent stats to say the least, but you wouldn't play a vanila 8 drop either, so it all depends on the tokens.
edit: Tokens are 0/1 Deathrattle: Add a random Legendary minion to your hand.
That's pretty insane for attrition control mage. Playability on the card depends entirely on the meta tho. If there are a lot of decks that counter this slow playstyle, it won't be viable. This is very good in a control mirror tho. So overall a pretty decent card, but might not fit in the meta.
Like many of the servants to the Lich King, Sindragosa's power is heavily tied to Deathrattle. Instead of just one Deathrattle effect, she comes with two! Her Battlecry summons a pair of Frozen Champions, that each give you a random Legendary minion when slain. Luckily they are 0/1, so you can pick them off with your hero power to quickly cash in.
I love it. People will vastly underestimate this card, but this screams value. 2 Mana draw a Legendary for 2 turns is ok, anti-AoE in following turns. Mages will have to decide between Medivh and this, depending on the other cards and meta this might just win in some lists.
And "add a random legendary to your hand" we have seen similar mechanics a lot already, this is lazy design, good for youtube highlights, but not exactly fun or competitive imo, especially with most dragons rotated in Wild.