Do I need an Assassin Class in my Retroclone?

EMO homebrew rules class revisions again for later this year

As I've slipped in a few more ad&d type classes, ive pushed my druids and priests to be weaker at fighting an better and magic. Ive made a templar and rover class to be closer to fighters paladins rangers in part dont want all holy men being entirely fighting guys. Im also making more martial classes as a reaction to how bad this has become on modern fantasy games so over the years in D&D games thieves have gone from magic user level pissweak to being a martial class. I can get my 5th ed 1st lv thef now to do 3 knife attacks with 3 or 4 x the HP of a bx theief. I was kind of heading this way myself but of late I thought another skill based class and thinking about what abilities do i want an assassin to have vs my rogue.  

My rogues are the skill maxing class and get the most slots to cover their skills, make stat rolls so 50%+ all skills minimum. They learn a skill every level. They have backstab +4 hit x2 dice damage which increases higher up. Finish an incapacitated target per lv per round. Any tarket reduced to 0 with a blunt weapon can be a KO instead of left dying. They also get a extra luck point per level per day which lets them take wild skill risks. Rogues make better kidnappers with ko abilities. Id rather they could fight ok like all the swashbuckling rascals in books not cowering weaklings like wizards with a d4 hp days.

Ive considered alt rogues types that apply the +4 extra damage multipliers could instead be applied to other skill in new ways. Some more useful in a SF setting or for NPCs:
Healer - bonus on hp from healing skills or do surgery faster
Pilot/Driver - operate one vehichle like boat, spaceship, aircraft, car, motorbike, chariot - multiplier can be used for extra turns or speed
Crafter - bonus on repair and craft skill of choice and multiplier can be used things faster, cheaper or quality
Merchant - multiply the monthly profits of your business by clever bookkeeping and weasly capitalist finance tricks

Assassin Ideas Obviously, anyone could do assassinations, but few have the spirit and secret training to infiltrate churches, nobles, cults, criminals or even wizards. Assassins are agents of cults, nobles, guilds, clans, secret societies or criminals and have strict rules on who they kill and how and when. You might say you are a spy as it sounds better than an assassin. This class will be effective spies also in a way break and enter theives would find harder.

I've considered abilities to make them not quite like thieves.
Better at fighting skills, not as many skills as rogue.
Skills will define specialisation, but likely will have
3x arms skills - (eg blades, swords, shortbow) +1/2 lv
4x arts skills - (eg disguise, sneak, sleight, bluff) +1/2 lv
4x languages +1/lv
+1 to hit per 2Lv and d8 HD (my fighters get +1/Lv)
light or medium armour any weapon up to d8
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Enhanced Disguise
A disguise includes a specific uniform, class dress or national costume. All assassins wear a masked or hooded costume used on secret missions, rituals or raids but not casually in public. This is the assassin's true identity. Most maintain several identities, like the one they spend their time in public, living with normal people. Other identities are adopted as required. Some learn skills to enhance these disguises with skills and spells, but Assassins have abilities that enhance their ability to infiltrate.

Variable skill slot 
Pick one arms, art or language skill which you can change with a day of study. This chosen skill works in a specific disguise or identity with clothes and tools appropriate to the skill or a professional user of the skill. Could use to get heavy armour to fake an armoured knight or a craft skill to complete a disguise.
-maybe get 2 slots at 10th, 3 at 20th

Hide alignment
Resist skills that others could learn your alignment while in disguise. For one hour per level per day, you can also ward yourself from Detect alignment with a Will saving throw. At 10th lv you get a save vs other alignment targeting spells if you normally would not get one. At 20th level, you save to resist scrying, divination or detection magic also.

Assassination
+1 to hit and damage per level vs surprised, ambushed, blinded or otherwise unaware targets. Target must not be able to see the assassin or be aware of them with other senses. Being unable to hear or being distracted by sound helps. Sneak and Hide from behind is the most successful combination of conditions. Easier to initiate in combat than with backstab
-maybe also target saves vs instant kill if target is half or less of your level -maybe starts with humanoid and advances through animals to living to supernatural creatures
-kill an incapacitated, unconscious, or sleeping target per level each round (my rogues do this, but can KO them instead with a blunt attack and KO targets brought to 0hp instead of them bleeding)
-The assassination damage and hit mod is conditional, but better than the fighter's chance to hit. work well with multiple attacks

Specialists would include versions of cult killers, ninjas, the original assassin order or could be specialist poisoners, snipers, and bombers, based on skill choices

Maybe my ranger paladin assassin clones will get extra att at 10th and 20th . Maybe the assassin needs damage dice bumps, too 1pt>d2>d3>d4>d6>d8>d10>d12>2d8>2d10>+d10 but not using this is cool too. Combining with a fighter, monk or thief might work well. Hopefully, this is familiar yet different in concept and weirder I will finalise with some players and have to weigh up vs other skill and martial characters

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I did playlists and dropped into my new class lists I ended up making my adept (monk) assassin and warrior the top 3 fighting classes, with rover (ranger-druids) rogue and templar (cleric-paladins) are the next tier of martials, with other abilities I have warrior class with the most combat skills and + to hit progression -adepts are martial artists - monks - wandering duelists - members of fighting schools -assassins are secret society masked killers & spies who strike enemies when they least expect it

Ill do my non humans once these done