And thats not all: remove flying counters from your creatures placed on them by Luminous Broodmoth, slow down the aging of Cumulative upkeep cards, like Mystic Remora (or Blizzard, if you feel like putting flying counters on opponents creatures like a monster), allow Undying creatures to continually un-die the (giant robotic manta in the) skys the limit
You can even add Teferi, Mage of Zhalhir to give Rootha flash, so she can repeatedly copy a Lightning Bolt for the win
Together, these four archetypes command 77.3% of the field
Guide of Souls also serves as huge energy ramp in an aggro deck
According to an interview with Hipsters of the Coast, Sandra Evingham, who would be Magic's second art director, edited the print of Unholy Strength "unfortunately leaving Doug's character with no context." It can be assumed she removed the Pentagram from the head of the Tutor as well