Megapede

Metal Sense. The megapede can sense any metal within 600 feet of it. It knows the direction to the metal and can identify the specific type of metal within the area.

Multiattack. The megapede makes one stinger attack and one bite attack. It can use its Consume Metal in place of its bite attack.

Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) slashing damage plus 3 (1d6) acid damage. If the target is a Large or smaller creature, it is grappled (escape DC 13). Until this grapple ends, the megapede has advantage on attacks against the grappled target, and it can't make bite attacks against another target.

Stinger. Melee Weapon Attack: +5 to hit, reach 10 ft., one target. Hit: 8 (1d10 + 3) piercing damage and the target must make a DC 13 Constitution saving throw or become poisoned for 1 minute.

Consume Metal. The megapede consumes one unattended Medium or smaller metal object or attempts to consume a metal object worn or held by the creature it is grappling. The grappled creature must succeed on a DC 13 Strength saving throw or the object is consumed. If the object is a magic item, the creature has advantage on the saving throw. Magic items consumed by the megapede stay intact in its stomach for 1d4 hours before they are destroyed.

Acid Spray (Recharge 6). The megapede spits acid in a line that is 30 feet long and 5 feet wide, provided that it has no creature grappled. Each creature in that line must make a DC 13 Dexterity saving throw, taking 18 (4d8) acid damage on a failed save, or half as much damage on a successful one.