Phenax EDH

I like Pact of Negation in every blue EDH deck.

It also sort of saves you a turn because you can play something on your turn without having to hold up counter magic.  I can see what you mean, but you could also say that holding up mana for another counterspell you have eats up a turn.  Anyways, I like it for exactly the reason you pointed out: people dont play around it- whereas with other counterspells they see you have blue mana up and may act differently.

siren is good but is has small toughness although it is hand attack too
that is true for pact but in this deck it eats to much mana after i use it i have so many high drops   plus secret tech blazing through a turn and leaving up dual land make people less suspicious of counters

Also was wondering if you'd considered Mesmeric Orb. Or if you need some more draw, Underworld Connections.

Crypt Ghast will work. The white mana symbol is only in the reminder text for Extort. The color identity rules do not look at reminder text. Of course, certain playgroups may rule differently.

Another ramp option is Dreamscape Artist. 

Also if you're looking at milling, the Tombstone Stairwell/Altar of Dementia combo works like a charm.  I imagine that one will  double the size of the bullseye on your back though.