>>64447477
>Imperium
They wouldn't waste marines on this, so probably about 150 million Imperial Guard I'd say if they didn't want to use orbital bombardment.

>Tau
They wouldn't even need to use troops, they'd just convince us to join willingly over time by offering us the chance to have sex with hot aliens.

>Orks
Probably twice as much as the Guard needs on account of their chaotic nature, but even if they're defeated the spores they leave behind will be a nuisance forever.

Reminder that sex with aliens is the most natural human instinct there is and no Imperium can claim to be of 'Man' unless it encourages it