Golos comes in as a FotD card, Manamorphose isn't underpowered but it's unexciting and I'd rather use the slot on something for a deck I'm trying to push.

Najeela was mentioned to me by a friend and I really dig it here, lots of fun Winota synergy too. Rabble is more powerful but Najeela does cooler things, so it's an easy swap.