There are a total of 15 pledge sources and feel that is adequate and probably the minimum needed (80% + chance) so its about right, and in testing seems to relaibly give me a pledge unit turn 1, and in 10 games so far have misssed just once.
I am only running 3 heirloom seeker, these are not key pledge units but still perform a function letting you attack un-blocked and are still ok to pledge though as the draw from the glasshopper still thins the deck and gives you a chance for a better unit.
The idea behind the name is the inclusion of secret passage. This enables some crazy combos as if you use this on an attacking dread it pretty much allows it to always hit face heal and deal damage without dying to a block due to its low defence, and if you give something unblockable later (which kills it after) that's ok too as when you have a killer unit whicjh has used its ability allows you to deliberately send it to the void to buy back and use again, or guarantees a draw from moonstone vanguard etc and I have managed to pull off some crazy combos already by making a vanguard and dread unblockable and looping them in and out of the void.
I have put the 4th glasshopper in the market as even though this is not essential it is an important part of the combo and makes the deck much more effective.
Haven't totally settled on the market choices yet but feel its pretty solid as Xenan temple gives you another killer effect gain some health back for the desecrate and gives some draw as does the Dizos office, there are two sources of modal relic and unit removal spells in banish and passage and the other choice I couldn't decide between a 4th varas choice for removing and silencing a threat or sandstorm scarf to shut down flyers which can be a problem for the deck or currently an in cold blood for those palace match ups as this is probably the flex slot for me it can be something else you may feel is needed