Maybe he just leaves diabolic texts lying about all over the place, driving the diabolist mad with temptation. The third most common cause of a return to the Infernal is despair. Having learned that they have wasted years in the search for Ascension, many mages return to Hierarchy in a sense of inevitability. This is the ultimate in angst - using Evil itself because nothing else is left to them. For them, the path to Hell is the quest for easy power.
Power is what they seek, and power is what they get.
These are the diabolists who are the most obvious, and often the most dangerous, since their quest for power leads them to powerful talismans and magicks. Those who worship evil itself can fall into this category. Believing they control the powers they summon, they fall into the trap of Hubris. These mages are often the most cunning in hiding the source of their power, and this are perfect as the sly, cunning, repeating villain of a chronicle. I figured, there must be an easier way.