I think you balanced a lot of these very well. Since they are legendaries the balancing is also more flexible because you can only put one copy in your deck. That said, I'd still like to give some feedback on what I like and don't like:
Sophistella: I like the idea of an end of turn choose one effect, and I really like the new heal druid archetype so I would love more restore effects like this one. I think lowering her health to 5 would make her more balanced though. Since druids can already ramp a 5 mana 4/6 can be hard for the opponent to react to and minions with end of turn effects can snowball pretty hard when they don't get answered. We'd have to see it in practice to know for sure of course.
Lady wildheart: Cool effect for spell based hunter decks and it seems balanced.
Battlemage Telumis: Cool and flavorful effect. Also seems well balanced to me.
Baldur the Blessed: Don't have a lot to say about this one. Seems strong but balanced for a legendary.
Tessa the Tender: Interesting effect, I like it. Maybe you could give Tessa lifesteal as well and lower her health a little bit, I think that could make the card feel better as a whole.
Solid Darkness: I really like the flavor of this one, but I would make it a 3/7, since 2 attack feels a bit too low to really benefit from the effect (of course attack buffs can change this, but rogue doesn't have a lot of those right now).
Frostland Colossus: I appreciate any freeze shaman support (since team 5 seems to have mostly abandoned it) and this seems like a really cool (pun intended) way to give that deck more of the power it desperately needs.
Netherlord Cindera: Cool and flavorful effect. I'm not really sure whether this would be balanced or overpowered to be honest.
Olga the "orc": I think this one is way too strong. Can you imagine pirate warriors using this for unlimited SMOrc? *shivers* Maybe you could change the effect to give stealth or 'can't be targeted by spells or hero powers' instead and increase the mana cost to 6 or 7.
Did a legendary minion for each class. Broken or balanced? Let me know.
Coming soon: Legendary spells :]
Warrior one would be stupid overpowered. Half the classes wouldn't be able to remove it..
I think you balanced a lot of these very well. Since they are legendaries the balancing is also more flexible because you can only put one copy in your deck. That said, I'd still like to give some feedback on what I like and don't like:
Sophistella: I like the idea of an end of turn choose one effect, and I really like the new heal druid archetype so I would love more restore effects like this one. I think lowering her health to 5 would make her more balanced though. Since druids can already ramp a 5 mana 4/6 can be hard for the opponent to react to and minions with end of turn effects can snowball pretty hard when they don't get answered. We'd have to see it in practice to know for sure of course.
Lady wildheart: Cool effect for spell based hunter decks and it seems balanced.
Battlemage Telumis: Cool and flavorful effect. Also seems well balanced to me.
Baldur the Blessed: Don't have a lot to say about this one. Seems strong but balanced for a legendary.
Tessa the Tender: Interesting effect, I like it. Maybe you could give Tessa lifesteal as well and lower her health a little bit, I think that could make the card feel better as a whole.
Solid Darkness: I really like the flavor of this one, but I would make it a 3/7, since 2 attack feels a bit too low to really benefit from the effect (of course attack buffs can change this, but rogue doesn't have a lot of those right now).
Frostland Colossus: I appreciate any freeze shaman support (since team 5 seems to have mostly abandoned it) and this seems like a really cool (pun intended) way to give that deck more of the power it desperately needs.
Netherlord Cindera: Cool and flavorful effect. I'm not really sure whether this would be balanced or overpowered to be honest.
Olga the "orc": I think this one is way too strong. Can you imagine pirate warriors using this for unlimited SMOrc? *shivers* Maybe you could change the effect to give stealth or 'can't be targeted by spells or hero powers' instead and increase the mana cost to 6 or 7.
I hope this is useful to you :)