To determine the total cost of a spell, start with the mana cost or alternative cost you're paying, add any cost increases, then apply any cost reductions (such as that of Cunning Nightbonder)
It might be a better choice for Living End to return to the black creatures instead, so it can make use of Grief
Of course, the MTG designers understood the assignment
I like having Ornithopter available since we can hold it in hand until the turn we want to cast Sephara, potentially surprising our opponents who werent expecting Sephara a turn early
Realmwalker is great in any kind of tribal decks and of course in Bear Tribal it can shine even more because of Ayulas abilities, the creature-heavy theme and the low mana cost of the bears
Call of the Ring will tempt you every turn , making one of your creatures into the Ring-bearer for escalating beneficial effects