I had the same problem until I realised I just needed to dodge the white discs. Sounds onerous, but even one as clumsy as I am (and believe me when I say I'm entirely rubbish at quick responses) managed it once I realised what I needed to do. So keep out of the way of the discs, incinerate the memory eaters and when they're not too in-your-face, concentrate on blitzing the towers as best you can.
