I find her actually pretty balanced after the changes, she can, if she has the mana for it keep a large group of summons. However it still takes progressing if she wants to support the yetis with idol summons, to reach a lane-devastating army.
And yet, when she has the mana pool to keep that up, she is still poor defensive after she used her heal, imo a ranger could easily hunt her down. Concerning your issue with yetis, is it a matter of them becoming "stuck" or not automated following her?.
Seems like I either have not got to this issue, or i'm keeping sure my units are always in reach to perform some cover damage.