I'm surprised there aren't any reviews for this card yet.

This is basically [Grotesque Statue 2] for one less XP, while taking up a slot with much less competition. That alone already makes it a very attractive upgrade.

Everything that made Grotesque Statue excellent applies here as well: it protects you from autofails, nasty symbol effects, and lets you push through critical tests when it matters most. On top of that, Mask of Silenus doesn't discard itself when it runs out of offerings, meaning it can be recharged with other cards instead of having to be replayed.

If your deck can support replenishing its offerings, this is an incredibly efficient source of consistency.