just finish this challenge with a dredge type deck too, i used my legacy dredge deck as a base, just changed the coliseums for baazars, and took out the led for more copies of zealots and stuff
just took me 1 try, the deck is fast enough to win quickly, u just mulligan till u get the baazar and keep the combo going,, iona felt totally useless, it just there because i use it in my legacy build, but with the baazars, i never felt the need to freeze the game with iona, the woodfall primus, is useless too here but really helped me in one game that i wasnt quick enough and the ai played a worship
enjoy

.398 4 Bazaar of Baghdad
.684 4 Golgari Grave-Troll
.678 3 Golgari Thug
.680 4 Stinkweed Imp
.681 4 Narcomoeba
.705 4 Bridge From Below
.700 4 Dread Return*
.666 4 Cabal Therapy
.675 3 Flame-Kin Zealot
.691 4 Ichorid
.120 2 Iona, Shield of Emeria
.682 3 Unmask
.722 4 Gemstone Mine
.830 4 Breakthrough
.403 4 City of Brass
.1040 1 Woodfall Primus
.1440 4 Careful Study