Boss order by stage
Mechanical boss order (1.4.5)
Terraria 1.4.5 has 3 mechanical bosses: The Twins (43,000 HP combined in Classic), The Destroyer (80,000) and Skeletron Prime (59,000 with all limbs). You can fight them in any order; most players go The Twins or The Destroyer first and Skeletron Prime last. All three must die before Plantera's Bulbs grow and before Chlorophyte can be mined.
The order
12. The TwinsMany players take the Twins first among the mechanical bosses because they are easiest to dodge in an open sky arena.43,000HP · Classic
14. The DestroyerA long worm with lots of segments: piercing weapons make it the easiest mechanical boss for many builds.80,000HP · Classic
15. Skeletron PrimeUsually the hardest of the three mechanical bosses, so most guides leave it last.59,000HP · Classic
Stats table
| Boss | Classic HP | Expert HP | Master HP | Defense | Summon item | |
|---|---|---|---|---|---|---|
| 12 | The Twins Hardmode | 43,000 | 64,500 | 82,238 | 10 |  Mechanical Eye |
| 14 | The Destroyer Hardmode | 80,000 | 120,000 | 153,000 | 0 |  Mechanical Worm |
| 15 | Skeletron Prime Hardmode | 59,000 | 88,500 | 112,836 | 24 |  Mechanical Skull |
See every boss, including the 14 event bosses, in the boss order checker.
Questions players ask
Which mechanical boss should I fight first?
The Destroyer if you have piercing weapons, The Twins if you have a good sky arena. Skeletron Prime is usually last.
When does Plantera unlock?
Only after all three mechanical bosses are dead; then Plantera's Bulbs start to grow in the Underground Jungle.
What do the mechanical bosses drop?
Hallowed Bars plus one Soul type each: Sight (The Twins), Might (The Destroyer) and Fright (Skeletron Prime).