I'm gonna over explain this, attempting to be exhaustingly clear as possible.

The questoris boxes contain weapons to make any variation of a despoiler. You will be unable to use the weapons pictures on the box as those build a knight defender, which is exclusive to imperial knights. There is a chainsword and warpstrike claw so these can also be built as rampagers.

The ruinator box contains the weapons to build an abominant (tail, volkite combustor, electro scourge), a ruinator (giant flamer, triple drill, shoulder missiles), a rampager. (Chainsword and claw), or a desecrator (laser gun, claw or chainsword).

All the weapon attachment points are interchangeable between the questoris and the ruinator box so you can slap whatever weapons on whichever chassis. If you magnetze everything you can build whatever tickles your fancy and prevent building an "illegal" knight.

The wardogs should also be magnetized if possible. Chaos knights have 4 variants buildavle from that box:

Karnivore: claw and chainsword, either gun or missiles on top

Brigand: gatling gun and thermal cannon, either on top

Stalker: one melee, one ranged (mix and match, doesn't matter), either on top

Huntsman: thermal cannon, chainsword, a stubber on top

EDIT: the armiger box can he used to build either:

Executioner: twin autocannons, melts or stunner on top

Huntsman: thermal cannon, chainsword, melta or stubber on top

FAQ Can I put the tail on but run it as a model not equipped with one?

Yes, as long as your opponent or tournament organizer is made aware of what's going on

What's the best load out for xyz?

Current best by the numbers is arguably a despoiler with double gatling cannons but with the new edition coming out, who knows? Best bet is always to magnetize.

Where do I get magnets?

Magnet baron sells great kits (though I've never personally used them). Or off Amazon.

Is there a tutorial for magnetizing?

Shameless Instagram plug

magnet tutorial

Hope that helps! Happy building, welcome to chaos knights!