This is a very linear deck to play. It's all about getting out a bunch of mercenaries and then landing a big Gray Merchant of Asphodel. If you are able to do that you win, if not you will likely lose. Having said that, there is the possibility of going on the aggro beatdown path with a bunch of X/1 mercenaries but that is fairly fragile and requires your opponent to stumble.

In general the play priorities are:
1. Gray Merchant of Asphodel
2. Mercenary fetch from library
3. Resolve mercenary fetcher
4. Draw cards
5. Removal
6. Attack?

Don't be overly hesitant to play Chainer's Edict early, it's there to slow the opponent down while you look for Gary.

The best opening hand (aka "the jphsnake") is two swamps, a dark ritual, and a three-mana mercanary. The first thing to fetch with the three-mana mercenary is almost always the Cateran Persuader.

Several of your mercenaries have evasion in the form of fear, flying, and can't be blocked by walls (tech!) use that to get in for a few pips of damage when you can.

This deck will get wrecked by sweepers. Don't overplay against Swamps or Mountains especially in games 2/3. Cateran Brute is nice here because he survives one point of damage and can rebuild your forces. Sometimes you just have to go for it though. Use your targeted discard on sweepers if possible.

This is a really fun deck to play but remember the Golden Rule of mercenaries: he with the gold makes the rules!

Delver Fae
-2 Misshapen Fiend, -1 Dark Ritual | +3 Dead Weight

MBC
-2 Rathi Intimidator, -2 Victim of Night | +2 Font of Return, +2 Tendrils of Corruption
Nihil Spellbomb if they use the graveyard

Burn
-2 Victim of Night, -3 Chainer's Edict, -4 Sign in Blood | +3 Duress +3 Tendrils of Corruption, +1 Nihil Spellbomb, +2 Font of Return

Kuldotha Boros
-2 Misshapen Fiend, -1 Rampart Crawler, -1 Dark  Ritual, -1 Sign in Blood | +2 Font of Return, +3 Tendrils of Corruption

RUG Tron
-1 Rampart Crawler, -2 Misshapen Fiend, -2 Victim of Night, -1 Dark Ritual | +3 Duress, +2 Choking Sands +1 Font of Return

Dimir Teachings
-1 Misshapen Fiend, -2 Victim of Night, -3 Chainer's Edict | +3 Duress +1 Nihil Spellbomb, +2 Font of Return

Eye Candy
-2 Rathi Intimidator, -2 Disciple of Phenax, -1 Dark Ritual, -1 Sign in Blood, | +3 Dead Weight, +3 Duress

Counterburn
-2 Misshapen Fiend, -1 Sign in Blood | +1 Font of Return, +2 Tendrils of Corruption

Affinity
-4 Rathi Intimidator, -1 Dark Ritual, -1 Sign in Blood | +3 Dead Weight, +2 Tendrils of Corruption, +1 Wail of the Nim

White Warriors
-1 Misshapen Fiend, -2 Disciple of Phenax | +3 Dead Weight

Goblins
-2 Disciple of Phenax, -1 Dark Ritual | +1 Dead Weight, +1 Wail of the Nim, +1 Tendrils of Corruption

Elf Bomb
-2 Disciple of Phenax, -1 Dark Ritual | +2 Dead Weight, +1 Wail of the Nim

Infect
-2 Disciple of Phenax, -1 Dark Ritual | +3 Dead Weight

Domain Zoo
-2 Misshapen Fiend, -1 Sign in Blood | +3 Tendrils of Corruption

RDW
-4 Sign in Blood | +1 Wail of the Nim, +3 Tendrils of Corruption

Hexproof Auras
-2 Victim of Night | +1 Duress, +1 Wail of the Nim

Golgari Existence
-1 Rathi Intimidator | +1 Nihil Spellbomb

Suicide Black
-2 Victim of Night, -2 Disciple of Phenax, -2 Rathi Intimidator | +3 Dead Weight, +3 Tendrils of Corruption