Why isnt the 4th cephalid coliseum considered a flex spot over the 12th dredger/4th breakthrough? Coliseum seems to be less desirable than breakthrough considering it requires an additional manasource to activate plus threshold although maybe dodging countermagic is whats more important? I am thinking 12 lands (9 gold, 3 coliseums) vs 13 lands (4 coliseums) 3 breakthrough. Damn but the main is tight in this deck..ugh.
Also 3 pimps/3 thugs seem ok since thug can bring back a pimp to the topdeck if necessary. Is this the mindset on dropping to 3 of each?
Lastly of all the archtypes in legacy I would think that dredge can recover from aggressive mulliganing the easiest. So along this line of thought and considering the ease with which dredge can find even a single card, wouldnt this deck benefit from the 61st card more than any other deck?
Edit- for reference here is what I am thinking of, any inherent problems you see with the list:
Lands 13
4 city of brass
4 gemstone mine
4 cephalid Colliseum
1 undiscovered paradise
Dredgers 11
4 golgari grave-troll
4 stinkweed imp
3 golgari thug
Business 13
4 bridge from Below
4 narcomoeba
3 ichorid
2 dread Return
Draw/discard 22
4 LED
4 careful study
4 faithless looting
4 cabal therapy
3 breakthrough
3 putrid imp
DR targets 1
1 flayer
Anyway I am coming back to dredge after a looong break due to helping a friend with his deck and 'flex' spots are our primary concern when dialing in the maindeck so if these questions are 'noobish' please forgive.