Dungeon Defenders

Beat it with the squire at level 70 solo (you probably can win on level 40-50, though). Summit was the hardest. Basic setup is to have 2 bowling ball turrets on each staircase. Probably only need to level each up once or twice. Cover the crystals with harpoons or use the apprentice to do deadly strikes. You'll need at least 2 harpoons each for each crystal. The ogres will come out the back side, so be sure to upgrade those bowling ball turrets first.

Finally, place some barriers/harpoons around the the outer edge of the map with your remaining defensive units. They are there to draw fire from the dragon so it doesn't attack your bowling ball turrets while you fight it. The apprentices barriers are very cheap, so use them if you are low on defensive unit points.

Just use the ballistas to attack the dragon as it crosses their path then activate bloodrage and attack up close when it lands. Should be fairly simple and your defenses should be able to hold out until you win.

A level 70 squire should be able to beat hard solo on all levels with proper tower placement. Insane may require help, so see that solution for those strategies.