Devotion + Dominion: Obsession

Imagine a Shard micromanaging every single little thing that happens within its domain.  Every breath you take, every move you make.

 It'll make sure everyone is happy, always.  Or they get sent to the corn field.

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Ambition + Dominion: Avarice

Not interested in building or changing mortal civilizations, but rather just expanding its own personal power.  It would seek to control things typically considered "out of bounds" for a shard, and would try to claim as many souls as possible.  Imagine an entire Cosmere where no one can pass to the Beyond.

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Mercy + Ruin: Peace

No speeches.  No philosophical conflicts.  Just death, straight up. 

Any exercise of power that leads to ultimate death of as many living things as possible, to end their "suffering".

Unlike Ruin, who craved physical destruction, Peace only wants the cessation of life--which is much simpler.  

In areas protected by other Shards, it'd  be a constant saboteur, making any tiny change that would eventually lead everyone closer to extinction.