The only reason that you are exiling is to fuel the Blight Herder. If you were willing to pay the extra mana for a Drowner of Hope then the deck would no longer have the exile sub-theme. If you did decide to do this, it would allow you to swap Mist Intruders for Dimensional Infiltrator. Also if you no longer need exile then you can swap out the Touch of the Void for Roast or additional Brutal Expulsion. I run an aggro version that uses Nettle Drone and exclusive colorless spells. DECKLIST Maybe I'll try out a more midrange version like yours so that I do not constantly end up with an empty hand.

I do like Drowner of Hope, espeically its tap creature ability and i'll consider that instead of Blight Herder but Blight Herder has been a great card for me so far with 4 bodies coming in over Drowner of Hopes 3 bodies, but i'll test it out.

I do like exiling from Mist Intruder, because it gives me early game value and late game, it can act as slightly better blocker than Dimensional Infiltrator. To me, the infiltrator is a mid-game, and mana-eating version of intruder and mid/late game is when I want my mana open for counter magic or other things, not for hopefully bouncing a 2/1 back to my hand, it's not as worthwhile to me in the 2-drop slot, but is a good suggestion.

Roast is a great card but I picked Touch of the Void because I can hit someone directly if I need and it could be cheap with a Herald of Kozilek or 2 out. I have Devour in Flames in the sideboard for 5 damage to creatures and planeswalkers to kinda make up for Roast, albeit slightly more expensive but can have synergy with Swiftwater Cliffs.

Thank you for your insights and suggestions.