Add runes of warding to the farseer, cheapest insurance you can get. Since you have two psychic powers on him runes of witnessing would be worthwhile as well.
Also strongly consider getting a unit (or two) of fire dragons.
Scorpions are fine, banshees are fine; but neither squad will help against all the armor that you are going to be running up against. One land raider would be tough for your list to deal with, two would be ugly. You are placing all of your
AT hopes on two prisms. Also, there is nothing wrong with splitting your
cc a bit, if you are going to take two
cc units then one scorp and one banshee is ok.
But ... you are going too heavy into the anti infantry mode here. Dont forget that your two squads of
DA with bladestorm are already significant anti infantry units. And the two units of pathfinders are good at plinking infantry as well. One unit of
cc should be plenty to add to that mix.
Taking your 172 points and cutting one banshee squad for another 307 would let you take two squads of fire dragons in well equipped serpents to go tank hunting.
In a pinch fire dragons are also good at taking out heavy infantry,
Meq or termies both fall to str8 ap1 pretty fast.
Prisms are excellent heavy slot choices, they are good at
AT as well as great at anti horde duty. With holofields they will survive against a surprising amount of fire as well. And scary prisms will tend to draw
AT fire away from your serpents as well.
Banshees win out over scorps against
meq precisely because of the
PW, yes. Mathhammer shows banshees better at killing
meq, scorps better at killing large quantities of troops such as orcs. Both benefit from having a farseer in their neighborhood tho.
There is nothing wrong with using Eldrad
btw, but only if you remember to keep him near more than one unit. His 3 powers a turn can be really powerful as long as he is in the right place. And being able to redeploy 2-4 units just before the game begins can be handy sometimes too
Sliggoth