This week's heresy is often repeated in other heresies (especially Gnostic-family ones). It's fairly simple, and deals less directly with doctrine and more with behavior (although practicers of Asceticism believed their behavior helped them earn or hurry along their salvation, which is a Pelagianism heresy as noted below, and utterly heretical).
Asceticism is the belief that abstaining from “worldly pleasure” can help bring about salvation and liberation from mortal coils. This was a common practice of some early church fathers (at least insofar as many sought to distance themselves from the world in any way they could), and is still used in some protestant churches today. This is a Legalism heresy, and by extension, a Pelagianism-family heresy as well.
The biggest issue is when focus on the Law over the Gospel becomes disproportionate. Any teaching that you can do something to help "earn" your salvation is dangerous, because it creates distrust and despair ("Did I do enough to make sure I am saved?" or something similar should never be a question on the lips or mind of a Christian). That is what makes Pelagianism and Pelagianistic heresies so dangerous.