I didn't look through all the cards, but good additions might include:
- Cavalier of Night
- Funeral Rites
- Gravebreaker Lamia
- Oread of Mountain's Blaze
- Thrill of Possibility
- Woe Strider
Grab a soul-guide lantern, Bojuka Bog, maybe a withered wretch, a few cheap artifact ramp like mind stone, wayfarer's bauble, and maybe expedition map to tutor the bojuka bog and others. Maybe another land finding creature like Skittering surveyor or Pilgrim's eye. Eew, map is $3. Maybe get a Rakdos Signet for $1.
Pre-con decks can be slow. I can't say for sure since I haven't played one in years, though having a good ramp package and some draw spells are important no mater what else is in the deck, and some cheap 2 cmc rocks will be a minimal investment that will grow with the deck. Don't forget some card draw! Magus of the Wheel should be really good in that.deck.