Well, as one mechanical concern, you can't use pharika's ability on your opponents' graveyards to generate snakes for yourself. When you exile a creature card, the creature card's *owner* gets the snake, not you. So only self-mill and exiling your own creatures gets you snakes to pillow fort behind. As your deck only has 9 creatures total, that's not a lot of snakes total, which make your sac engines, etc. kind of weak.
Plus, your deck is *very* artifact and instant/sorcery heavy, while being light on colored permanents. So, that means activating pharika's devotion will be very hard. If she's just an enchantment, and not a creature, she's missing her best features.
Mill may be kind of tricky in these colors in general. Most of the best mill cards live in blue or dimir. Not saying it's impossible, but it will have to lean heavily on artifacts... which is a non-bo with pharika, and since she wants *self* mill to have snake exile targets, she has very specific mill needs. (Or general "lots of her own creatures dying in combat" needs, which doesn't work well with a low creature count)
There's plenty of specific card choices to argue about one way or another (some of your mill package is *much* better than other parts of the package, and I'm not a fan of fyndhorn pollen in a deck where one of the central plans is "have lots of 1/1 deathtouchers ... that are now 0/1 deathouchers"). But, I'd work through about the big picture before worrying on the details here.