This comp uses 6 Mages in order to beef up Annie as your main tank and Veigar as your main dps. You can either run a Chosen Elderwood or Mage in order to hit 3 Elderwood.
This comp is quite flexible and doesn't require a Chosen unit, but you should try to mainly have Rods, Tears, and defensive items.
Level up to 4 early if you want to start a win streak. Level up to 5 to try and continue the streak.
If you're weak in the early game, you can opt to save gold and lose streak instead.
At Round 2, level up to 6 regardless of your start. Put together the strongest team you can.
Hit level 7 at Round 1. Start slow rolling for Annie and Veigar. If you hit Annie quickly, you can level to 8 and continue looking for Veigar, or you can continue looking for Veigar at 7 if you don't have enough gold.
Mages are generally quite weak in the early game, so don't funnel too hard into the early game. Cultists can be quite nice early game to compensate for the lack of damage, but feel free to use whatever units you find.
Annie will be one of the core units of the team, so be sure to pick her up early when you can and pair her with some good damage backline units. For this comp, the earlier you can hit Veigar, the better.
If you run a Chosen Elderwood, you don't have to worry about changing any units. With a Chosen Mage, you can drop Twisted Fate for an Elderwood of your choice like Hecarim, Ezreal, or Nunu.