The best foundation I've found for covering acne and scarring is theEstee Lauder Double Wear Maximum Cover. It's quite a thick foundation so you only need a small amount but the coverage is excellent. Although if you're taking Roaccutane this foundation might be too drying. Have you givenVichy Dermablenda try before? The coverage is amazing and is not as dry as the Estee Lauder - it's also less 'cakey' so if you have large pores or scars then this will fill them in a bit better.
(Make sure you don't get the 3D version in the Vichy as that's for acne control and might be too much with Roaccutane.)

Estee Lauder also does another foundation in the Double Wear range that is less thick but gives great coverage which is buildable -Estee Lauder Double Wear Foundation.

I'd advise reading about undertones for a few reasons, but the main one being:
If you use a foundation for cool undertones (but you have a warm or neutral undertone), when you build the coverage the foundation will look grey-ish.

Good luck with your treatment!

It's more about technique. Take a makeup sponge cut in half. The use of a good corrector(green or peach) then stippling/pushing/rolling motion of foundation and blend out the edges. The unsmooth texture of the cut sponge
will cover any acne or scarring.
I am professional make-up artist who isprone to cystic/nodular acne. Highly sensitive skin. I had 4 rounds of accutane. This technique I have used on myself and clients.

MAKEUPFOREVER hd liquid,HD creme and primers are heaven sent. Also have used George Armani luminous silk foundation (pricey) they look flawlessly airbrush both in person and on HDcamera. (Skin-like effect not Cakey)Loreal true match is a good drugstore foundation too.A loose setting powder to set and a setting spray will keep it on place all day for all skin types.

Hope this help!!! XX

Does makeup forever hd foundation clog pores ???