Gaining motes in the rift

Hello people, I have been grinding in the rift for a while now and I have gained a total sum of 8m motes (with the intent to purchase a Rift Prism) so I most likely have approximately 5m to go from what I have heard. I have been trying to grind motes by highlite grinding even though it is extremely boring and requires a lot of attention I know that it is painful for a reason with the prisms heavy price tag. I am wondering if there are any other methods (preferably one that requires practically no real attention to the game even though it is a little "cheap" to do in my opinion) to get motes. I am going to continue grinding highlites to sell just because of how good the method is but does anyone know of a way to basically afk motes (I already know about the ubik cube and I am also consistantly doing that)