First a list:

4 Golgari Grave-Troll
4 Stinkweed Imp
2 Golgari Thug
1 Darkblast

4 Tireless Tribe
4 Putrid Imp
4 Careful Study
4 Breakthrough

4 Bridge from Below
4 Cabal Therapy
4 Ichorid
4 Narcomoeba
2 Dread Return

4 City of Brass
4 Gemstone Mine
4 Cephalid Coliseum
3 Tarnished Citadel

Sideboard:
1 Dread Return
1 Ancestor's Chosen
1 Flame-Kin Zealot
1 Sphinx of Lost Truths
1 Terastodon
1 Ray of Revelation
4 Ancient Grudge
4 Firestorm
1 X (I think I have another Ray or a Nature's Claim here or a Chain of Vapor)

If you expect more than 1 of Enchantress/Stax/Lands, it's worth putting the Terastodon in the maindeck over a Careful Study or a Golgari Thug. You can't beat a Moat game 1 without it. The Terastodon is better against Lands/Stax but worse against Enchantress than Woodfall Primus.

The 3rd Thug/1st Darkblast is a toss-up: Darkblast dredges worse but it has some utility killing creatures and it's an outlet on its own. The blue decks can only ever beat you by keeping you from being able to dredge in the first place, so being able to just cast Darkblast on their Tarmogoyf just to start the chain is fine.

Against beatdown decks, Ancestor's Chosen comes in as a Dread Return target to keep them from racing.

You only ever want the 3rd Dread Return when you HAVE to win that way fast. Against combo, I bring it in; I might also consider bringing in the Dread Return + FKZ + Sphinx just to speed your clock up. You don't need a lot of redundancy in drawing multiple lands/outlets there. The full package of Terastodon + Dread Return + FKZ + Sphinx is only against Lands/Enchantress/Stax style decks. You need to kill them in one turn by killing their Glacial Chasm and then immediately winning with Zombies (to beat, say, Tabernacle) before they can cast Loam.