Upgraded Iron Defender

Keen Senses. The defender has advantage on Wisdom (Perception) checks.

Telepathic Bond. While the defender is on the same plane of existence as its master, it can magically convey what it senses to its master, and the two can communicate telepathically.

Recon unit. One of the the Defender's eyes is detachable. It counts a tiny creature. It has 10 hp, STr -4, Dex +4 Con -2, Int 0, Wis +4, Cha 0 has a fly speed of 30 and can hover. it has darkvision. Stealth +8 Perception +8

Ram. If the Upgraded Defender moves in a straight line for 20ft before reaching a creature, as a bonus action, it can make a special ramming attack against any creature in the Defender's path for the rest of its movement. 
Melee Weapon Attack: +9 to hit, reach 0ft, Hit: 17 (2d8+5) Bludgeoning damage. If the target is a creature, it must succeed on a DC 17 Constitution save, on a failure the creature has disadvantage on Strength and Dexterity saving throws.

Mount. The Defender has been retrofitted and programmed to be a mount, its back has been shaped to seat. It is an independent mount. 

Multi-attack. The upgraded Defender can take two attacks with its attack action, one with its Bite, and one with its claw

Bite. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 14 (3d6 + 5) piercing damage. If the target is a creature, it must succeed on a DC 17 Strength saving throw or take an extra 10 (2d10) piercing damage and be grappled (escape DC 17). The defender can have only one creature grappledin this way at a time.

Claw. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 12 (4d4 + 5) Slashing damage. If the target is a creature, it must succeed on a DC 17 Dexterity saving throw or be knocked prone.

Reactive Plating: As a reaction to taking magical or non-magical slashing, piercing or bludgeoning damage, the defenders armor can reconfigure it self to be resistant to the damage type just taken.