Use it when the pull widens
Engineering adds control after the class kit is spent. Iron Grenade stuns nearby enemies. Target Dummy redirects nearby threats while you bandage, drink, or leave. Goblin Sapper Charge hits nearby enemies for 450–750 Fire damage and also hits you for 375–625. Carry the tools for a pull that has already widened.
Core tools
Big Bronze Bomb at 140, Iron Grenade at 175, Thorium Grenade at 260. Each gives an area stun and a ranged interrupt any class can carry.
Use Target Dummy for a threat handoff. It can buy a Healing Potion, an eight-second bandage, or enough distance to leave.
Use Goblin Sapper Charge when several enemies are already on you. It requires Goblin Engineering and has a five-minute cooldown.
Keep the kit current
Stock in town and upgrade explosives as the skill rises. Old dynamite leaves a higher-level character without the control the profession is meant to provide.
Who benefits
Warrior and Rogue get a ranged interrupt and another control cycle. Hunter gets area damage during the stretch where class AoE is thin. Mage gets a backup after Blink and Frost Nova are committed. Shaman gets room when totems cannot solve the pull.
Check the bag
Bring grenades before the cave.