The War of Assassins is costly. Some costs can be calculated: wealth, resources, lives, assets, military equipment, etc. Some costs are more difficult to compute. The Atreides pay dearly, not only with their morality, but also their identity. The honor that shines bright on Caladan, rusts over when exposed to this protracted skulduggery. Even if they win, what will be left of them.
I must advance things. I must employ moves on more distant game boards.
What House Atreides needs, to survive and to win, is leverage. I must provide them with leverage that swings a fulcrum on an Imperial scale. There are hidden enterprises occurring on this planet — in the orbit of Count Fenring, in the mysteries of fallen Carthag, in the hushed cargo of certain crashed ships — which have the faintest scent of what I seek. I will root them out like a maddened hound.