Osutra: Isn't this a bit close to Oscuda, the AoE poison cloud skunk?
Thematically speaking: Owls are not powerful spellcasters like Ravens, rather they are highly reliable and durable messengers. Therefore I think it should have the following abilities:
9 Mana, 8 Health, 1 Armor, 0 Channeling
Animal, Familiar, Flying, Regenerate 1
Peck (quick attack): 2 melee dice
Osutra may only cast non-Epic level 1-2 Incantations.
Owl's Message (special ability): When the Mage casts an Incantation, she may choose to use Osutra's range and Line of Sight instead of her own. When Osutra casts an Incantation, it may choose to use the Mage's range and Line of Sight instead of its own. This ability cannot be used while Osutra is Incapacitated.
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Skree: Skree should be able to unavoidably instakill low health creatures, swooping out of the sky to destroy them. This would make her a powerful counter to Ferret and Bobcat type creatures, as well as most Familiars.
11 Mana, 9 Health, 1 Armor
Animal, Bird, Flying, Fast
Diving Talons (quick attack): 4 melee dice, Unavoidable
Flawless Precision (special ability): When Skree declares an attack, her controller may choose to deal fixed damage instead of rolling dice. If so, skip the "Roll Dice" step of the attack and apply 2 Normal damage and 2 Critical damage during "Damage and Effects".
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Note that this ability is weak against Armor (2 armor reliably halves the damage), but is completely unaffected by Aegis, Agony, or Dawnbreaker Temples. It is also unaffected by Bear Strength.