How to Use Training Camp
Training Camp buffs two minis - one on each side of it. This makes placement of Training Camp vital to your success with it. If it gets taken out, the buff dissipates. Protecting it with Witch or a tank might be necessary. It does have enough HP to shield a ranged mini in your back line, especially if the gizmo's boost empowers that mini to ward off approaching opponents.
Playing against Training Camp is a lot like playing against any empowered opponent and as such your strategy will vary per unit. High-damage clash abilities such as Spear Goblin's Spear Toss or Bowler's Strrrike!!! can soften the Training Camp, and Magic Archer's piercing Magic Arrows can passively damage it, but expending time and energy to take it out at the expense of taking damage in the process is not recommended.