In most cases, Wonder-crafting requires vulgar magick. Unless high-tech machines are involved (and often even when they are), such procedures tend to feature spectacular pyrotechnics, chanting weirdoes, eerie manifestations, arcing bolts of energy, and other things that make folks go “What the fuck was that?!?!” As a result, the investment process is usually vulgar magick. For that reason, among others, mages prefer to use specially prepared Sanctums /Laboratories, Chantries, and Nodes (as per those Background Traits) when they add the magickal elements to their creations.

Aside from Charms, Fetishes, and Trinkets, most Wonders require a vulgar Prime 4 or 5 Effect to seal the deal. Every other Effect sealed into the Wonder must be invested into the foundation as well, which also tends to use vulgar magick. As shown by the rules in Mage 20, the difficulty of casting magickal Effects (of any variety) is as follows:

Coincidental: Difficulty = highest Sphere + 3 Vulgar Without Witnesses: Difficulty = highest Sphere + 4 Vulgar With Witnesses: Difficulty = highest Sphere + 5

Thus, unless your mage in working in her Sanctum (where her Effects are coincidental), most investment procedures have a base difficulty of 8; even in the Sanctum, that base is 7. Certain modifiers can reduce that difficulty by a maximum of -3. In short, then, making Wonders isn’t easy… and, more often than not, it attracts Paradox as well.