Handler Class

This class would be ridiculously strong. 

A: The Hound, Programs, Thetur-Enhanced Brain, WolfWhistle

B: Enhanced Wolfwhistle, Mod 1, gain two abilities at rank 1

C: Enhanced Motility, Rank up an ability and gain another at rank 1

D: Mod 2, Rank up two abilities

E: Rank up two abilities, then gain all abilities you don't have at rank 1.

The Hound

You have a Hound, a cybernetic canine that is has 5 HD, weighs 300 pounds, AC of Plate, is about the size of a wolf, and moves 30ft per turn. When it changes size, it might not necessarily be a model of a dog anymore. Small ones go down to Puppy size, and large ones can be as big as a bear. You command it using your Wolfwhistle and a set of Programs which translate audio cues into action. Your Hound always goes immediately after you in combat.

Hounds always have a bite attack. When they bite an enemy, they can Grapple them.

Protocol

You have 1 Protocol per Template in Handler. Protocol details a list of actions your Hound can take, the order in which they occur, the targeting prioritization, and the WSM (Wolfwhistle Save Modifier) that results from the whistling frequency which triggers the protocol. 

• Every Protocol has a name. This is just a keyword so the Handler can know which program they're running.
• Action Strings: These detail the action the Hound takes on its turn. make it clear what principles guide its movement (like staying behind cover, or staying near a fixed point, or balls-to-the-wall aggression). Make it clear how it prioritizes targets, what it does with its turn. If it uses its Bite attack, it may attempt a grapple afterwards, or simply move away (w/ an attack of opportunity). 
• WSM: by default, the WSM is 0. One of your programs may instead have -2.

Thetur-Enhanced Brain

Your brain is hopped up on the energy of a Thetur sphere. You have advantage on all perception checks, must consume twice as much food, air, and oxygen at all times, are vulnerable to psychic damage, and have disadvantage on saving throws related to perception or metabolism (like flashbangs or poison).

WolfWhistle

Normally, your WolfWhistle is off. You may turn it on with mental activity, at which point everyone around you has to make a perception-related save or lose an action. Succeeding the save gives them advantage on subsequent saves. the normal Cyberwhistle range is 60ft.

Enhanced Wolfwhistle

One of your WSM's can confer disadvantage to the check instead of a flat modifier.

Enhanced Motility

When you command your Hound to Attack, you may command it to Pounce if its size is

-1 -----> +1, and Crush if its size is +2 or greater. Pouncing turns the last 5-20ft of movement into a leap and deals an extra d3 damage on a hit. Crushing occurs the turn after a grapple and deals damage equal to twice your size to the target.

If your Hound's size is -2, it does not trigger opportunity attacks by leaving someone's area after a Bite attack.

Size Chart:

-2 Size: Size of a small dog or huge rodent. (~3ft torso)

-1 size: size of a large dog, like a german shepherd. (~4 ft torso)

0 Size (default): the size of a jungle cat. (~5ft torso)

+1 Size: size of a wolf. (~6ft torso)

+2 Size: size of a black bear. (~7ft torso)

+3 size: size of a huge grizzly bear (~9ft torso)

+4 Size: larger than an elephant (~11ft torso)

Abilities:

1. Chassis rigs
1. +1 Size, +5ft Speed, or HD. 
2. +1 Size & HD, -5ft Speed; or +5ft Speed; or +10ft Speed, -1 Size & HD
3. +2 Size & HD, -10ft Speed; or -1 Size & HD, +10ft Speed; or +1 HD.
2. Programming Nerd
1. +1 Protocol
2. You can now use conditional suites. These break your Protocol into different groups based on environment conditions. This means at certain times (which you determine) your Hound can have different protocol for target prioritization, attacks, defense of its Handler, etc.
3. +2 Protocol. Your protocol commands enact at the end of your turn, not the start of your next one (meaning your Hound, who goes immediately after you in combat, changes protocol.
3. Cyberwhistle Modder
1. -1 to all your WSM's (improves 0 to -1). Does not effect advantage, disadvantage, or no threat protocols.
2. Your whistle can enter frequencies that are inaudible to creatures, but still register to your Hound.
3. Double the range of your Cyberwhistle.
4. Powerful Frame
1. Can attempt a Tear after an attack. Rips off a limb: 1-2 hand or foot, 3-4 foreleg, 5-6 forearm, 7 full-arm, 8 throat.
2. Pounce damage improved to 2d3, and you can move an extra 10ft as part of a pounce (s0 the normal maximum Pounce of 20ft would be a 30ft pounce, even if you only had 20ft of movement left).
3. Hound can do called shots at different limbs. -1 to hit hit a limb, additional -2 to hit a hand or foot specifically. -4 to hit the throat.

Mods:

1. Handler's Failsafe. Your Hound has a built-in cybernetic whistle that activates when it loses connection with yours. It can run one Protocol, or two if you have access to conditional suites.
2. Skulker Cloak. Your Hound is mostly invisible to the human eye. It becomes visible if it executes any sudden movements. It also emits a field of silence within 20ft, which dampens wave frequencies in the range just below whistle-pitch. You may add Cloaking and Decloaking to your Hound's Protocol strings.
3. Pups. Your Hound may deploy Pups from recesses in its frame equal to [Templates] - 1. Each of your Hound protocols has an analog Pup protocol. This means every action string your Hound does always happens in tandem with a specific Pup string (unless you have Conditional Suites). Deploying Pup is a Protocol in of itself, and costs one of your Protocol slots.
4. Extendable Neck. Your Hound's neck can extend 15ft like a yo-yo. This includes around corners. You may add "Reel In" to your Protocol strings, which either brings your Hound's Head (and whatever it's grabbing) towards your Hound's body, or your Hound's body towards the head (if whatever it's grabbing is heavy enough).
5. Emotional Scanner. Your Hound can read human emotions, and relay them to you. It can prioritize targets by their emotional state.
6. Blink Drive. Your hound can teleport 10ft on its turn, or as a reaction on someone else's turn. You may add "Blink" to your Protocol strings.
7. Saw Claws. Your Hound has a secondary weapon-- a pair of extendable and retractable whirring sawblades. These can only be used in situations where your hound starts its turn in a favorable situation (such as having a target grappled, or singlemindedly attacking one enemy who is distracted). You may add "Saw attack" to your strings, which are two, d6 damage attacks, and can be done as a post-bite action in your Protocol string.
8. Hypodermic Shot. Your Hound can administer fluids through a hypodermic needle in its canine tooth using a bite. One of its bite attacks can be filled with some kind of poison, or with supermedicine (restores d6 damage). The bite which administers the needle deals no damage. They may do this once, then the needle needs to be refilled (during an exploration turn or a short rest). You may add "Hypodermic Shot" to your Protocol strings.
9. Scenter. Your Hound can track scents. The trail ends if new scent data is entered, the target is found, or the target literally eradicates the scent from its body (by scrubbing themselves down in super-strong soap and changing out their sweat glands). Even then, the trail ends at the discarded sweaty tissue. It can priotize the scented target in its protocol strings.
10. Colossus. Your Hound gets +1 Size. at Size +5, your Hound is the size of a tank. If it's size +3 or greater, you can fit inside it.
11. Piloting Remote. You can pilot your Hound manually using a handheld remote. Pounce, Grapple, Tear, Attack, etc. are all mental actions (which you get two of per turn because of your Thetur-enhanced brain). 
12. Avian Mod. Your Hound is a Raptor. Your Raptor protocols are the same, except it can fly, and its default attack is Talons, not Bite, and instead of Pounce, it can Dive. You may add "Alight" and "Land" to your Protocol strings.
13. Unhinged Jaw. Your Hound can unhinge its Jaw to grapple better. It can grab any limb on a person's body in a grapple with a random 2d6: 1 throat, 2-3 hand or foot, 4-5 forearm, 6-7 bicep/thigh, 8-9 foreleg, 10-11 nether region, 12 head. Called shots are -4 for head and throat, -3 for hand, foot, and nether region, and -1 to a limb. Can also Crunch grappled limbs the turn after they're Grappled, which renders the limb useless and deals 2d4 damage (or 2d6 vs head, throat, gonads).
14. Electromagnet Socketry. The Hound's limbs are held to its torso by powerful electromagnets at their joints. Hits that would normally damage a limb beyond repair instead knock the limb off the body. It also has full 360-degree range of motion around the joints. You may add "Power off X Joints" and "Power On X Joints" to your Protocol scripts.
15. Bark. Your Hound can bark & growl. You may add "Bark X times" and "Growl" to your Protocol scripts.
16. Pacifist Protocols. Gain +2 Protocols. They cannot be used in combat. Gain the "Retrieve X" "Dig(Dimensions)" and "Doggery" keywords. Retrieve X retrieves a designated object, which you must present an image of. Dig(Dimensions) digs a hole with certain dimensions. "Doggery" is a keyword that represents a vague set of dog-like actions your Hound can mimic, such as playing, tail-wagging, cuddling, accepting belly rubs. Doggery can be used during a short rest to provide emotional care if the target has an emotional bond with the dog, and rolls Over wisdom/mental stat (if playing roll-under).
17. Pretender Kit. Your Hound has a realistic suit that make it look like a real animal (unless examined by a vet or taxidermist or similar professional). It will get torn very quickly in combat, and your Hound does not act like a dog by default.
18. Pneumatic Enhancements. Your Hound's movement can be one huge leap. It can cover the same distance it would normally cover with a movement in a leap. at its peak, the Hound jumps 20ft in the air. For every 5ft beyond 20 that the Hound jumps, its pounce deals an additional damage.
19. Brain Scanner. The Hound does not need to hear your whistles to know which Protocol you want. It analyzes your emotional/intentional state and acts based on that. You can still choose to have your whistle active though.
20. Cybersenses. Your Hound can detect ultraviolet, infrared, radio, and x-rays, as well as seismic disturbances  and alpha, beta, and gamma radiation. You may add Detect (type) to your Protocol strings, and use that data for target prioritization.