When do you pick [[Eidolon]]?

I'm struggling to understand when [[Eidolon]] is valuable, it's a rare card for Necrobinder that exhausts your hand and gives you 1 intaglible if 9 cards were exhausted for two (one) cost.

Now I know exhausting bad cards is good, and I realise that Necrobinder has a souls build which allows them to fill their hand quite a bit - but is that the only conditions that need to met to make the card work or is there something I'm missing?

Necro has no exhaust engine to benefit from, and the card only works if you're exhausting 9 cards which can be super conditional, so I'm confused about what build makes this work since I can't see this more as a dead card.