I'm always up for a little Horde mode and I've already had all of the levels maxed for fortifications for some time now, so my cheevo popped straight away when I went into a private Horde match with just me, myself and I, then left.

For people who want advice on how to get it, best thing to do is play as hard a difficulty as you can handle, and use at least two, if not three hard mutators. When I was still working on everything, I liked using any two of the following - No Ammo, Vampire, Friendly Fire, Must Active and then also have Instagib (so I'm not crushed into dust when 'Zerkers show up.)

Then, I just loaded up Blood Drive (haven't really tried Horde on the FoN maps yet, so not sure if there's a good map for Horde yet) started on Wave 1 and worked up to where the Silverback was available, then went into the red spawn (default Locust spawn if playing Execution) and just gunned down everything that moved. Even when playing on Insane, it took a lot for the enemy to push through, with them being funneled into one small hallway like that. Make no mistake, maxing out your Silverback means playing for the long haul, but the harder mode and mutators you play with, the faster it goes. I had a partner who helped me out with mine, then I helped them get theirs in return. Given how much a grind it is, it's always best to not go in alone if possible. As I already have all of mine maxed, any money I get I'll gladly donate to the cause.