Ashcloud Phoenix is great in any deck built around those types of mechanics, because unlike most Morph creatures it can go back and forth between being face up and face down
If you go over 13 mana value, you dont get to cast the spells you exiled
Baleful Strix is one of those cards that would be pretty miserable in a lot of Constructed formats that ends up being a lot more reasonable and fun when playing singleton
I recently talked at length about replacing staples on The BM Cast, if youd like some extra resources on this topic
For instance, in an Archimandrite deck you could gain a bunch of life in your upkeep and first main phase to add a big +X/+0 buff to your commander, then use Alteration to turn it into Giggling Skitterspike
It may feel insignificant, but youre now essentially keeping everyone down one card until this creature is dealt with