Amodex is billed as an all-purpose stain remover, and I . . . don't love it for that.  I tend to prefer low-viscosity enzyme stain removers for typical stains, or specialist removers for stains from non-animal/plant/food sources. 

What I do love Amodex for is ink.  Sharpie, dry-erase, ball-point, gel, fountain pen, marker, printing inks - Amodex is the demonstrably superior product at getting out ink, and it's worth having for this purpose alone.   Even after other products have failed, Amodex is worth a shot.

Amodex works and is applied differently than other stain removers.  They reccomend a brush on the website for tough stains.  I'm going to throw a flag on that play and suggest use of a Bone Folder  or the edge of a spoon as a much safer choice to avoid altering the surface finish of fibers.   

When treating ink stains with Amodex, I like to work from the back side of the fabric; place a couple layers of paper towel directly on the stain, and work the Amodex through from the back side, moving the toweling as the ink transfers.  Don't scrub like you're cleaning grout - just keep applying and working the creme through the stain until it is all on the paper.  Heavy  stains like from a pen leak may benefit from a two-step process - after  progress seems to stall in the first set of applications, rinse out the product and ink under running cool water, allow to hang dry, and begin again.

Detailed instructions and links to video on the Amodex website.