The left side shows 7 steps to staying alive. Your healer might be clueless, your team may be useless in team fights and you might get killed every time that you go to fulfill an objective. Hopefully this build will help. Level 1: Regeneration Master will help you heal faster. You might be stuck on your own a lot and your healer maybe a clueless dolt. You are gonna need all the help you can get staying alive. Level 4: Superiority will minimize the minion, merc and tower damage you take while you are all on your own in a lane. Level 7: Bed of Spikes will give you a chance to escape when you find yourself suddenly ambushed by the enemy. Level 10: Web Blast will also help you keep your death count down when you are in a serious pickle. Level 13: Spell Shield is gonna help prevent those quick deaths that are inevitable when you find your team down by 3 levels. Level 16: Imposing presence is gonna reduce how many hits you take as you attempt to escape back behind your wall. Level 20: Hardened Shield is just one more layer of protection that will prevent you from feeding the enemy more XP. I think Rewind is also a very viable talent here, to keep you on the battlefield and out of the Nexus.
This build is gonna allow you to stay on the battlefield, deal damage and attempt to get the objectives. As the other teams starts to crush you and gains 2 or more levels on you, deaths are going to come much quicker. This build tries to keep you in the game after that happens. The other option is to try and keep that XP gap close by amassing lots of damage and gaining XP for your inept team.
Maybe your team doesn't understand that camps will help crush walls and that soaking XP in a lane will get you a level advantage over your foes. If you think you can close the gap on the XP then try this build (seen on the right of the image above). Level 1: Assault Scarab will give your beetles an attack boost. This means that you are going to get through more minions in your lane as you crush the incoming traffic. Level 4: Locust Needles will give you a huge advantage when smashing through a lane. You will get splash damage on your basic attacks. This makes blasting through walls of minions a lot easier. Level 7: Urticating Spikes are going to expand upon your needles by dealing area damage when you activate your shell. Level 10: Locust Swarm is going to compound your area damage even more while healing you at the same time. Level 13: Burning Rage adds another level of destruction surrounding Anub'arak. I rarely use this ability except for solo situations. The one downside of this ability is that it is always on, so if you are running away from an enemy and brush by a merc camp, it will auto-attack them and they will pursue you as far as their leash will allow. Level 16: Epicenter will complete the trifecta of beastly area damage. When you burrow, you will pop up and deal massive area damage, followed by your shield which deals area damage and your attack which will do splash damage. Also your burning rage will do area damage by simply existing. You are now, as Gazlowe would say "a one man wrecking crew". Level 20: Rewind will allow you to have all of those abilities back right after you use them, making you a damage grabbing guru. Hopefully you can marginalize the XP difference and keep your team of scrubs in the game long enough to pull out a win. Here is the YouTube version if you don't like reading.