Editing Warhammer 40,000/Tactics/Kill Team(8E) Guide and FAQ (section)

==Can I make a list out of just [some unit]?==
Yes, unless there’s a model limit on it. Should you? Unless that’s the only good datasheet available to you (see harlequins, custodes, grey knights) then no, it will almost always be worse than using all of the good options available to you.

===Can I make a list out of just terminators?===
Yes, you can have three terminators if you select wargear to squeeze under the limit. Should you? Fuck no, it’s terrible and boring for both players. Board control is key in KT and you can’t do it. You don’t have interesting choices to make and neither does your opponent. Teams that only field 5 models are at a distinct disadvantage, 3 models is terrible in almost all circumstances.

'''I don’t care how good it is'''

Then go for it. It's still boring to play with and against though. Fluffy if the other guys got genestealers though (remember that all of the fluff for space hulk has the terminators taking terrible loses and be ready to recreate that)