The infinite combo in Mark's feature deck is easier to pull off than many of the older ones mainly because Krixel costs 4, while Kronore costs 7. That means your opponent will be goldfishing for less turns, which in turn makes your hero more likely to survive (although the odds for that are still very bad) until it's time to pull off the combo. Krixel's drawback, on the other hand, is his uniqueness. So no
Masquerade Gown tricks with him like you can do with Kronore.
That being said, here are some suggestions from an old-school combo player for improving the deck:
1. Make your support pieces less vulnerable. Drop Breanna Greenmother for
Hand of Edward the Odd.
Reasoning: Instant ally in opponent's end phase is pretty much the same as playing exhaust power allies with Breanna on the table. Whilst Breanna can be attacked by allies, combo deck equipments tend to stay on the table longer vs pre-sideboard opponent.
Benefits: instant Recall form the Brink, instant Arena allies with helpful continuous powers (e.g. Gladiator Katianna), instant Totems. Also, anything that makes this particular combo piece survive makes the rest of the combo significantly easier to pull off.
2. Try to prevent dying in combat. Since shamans are Draenei, you can introduce
Ossus the Ancient.
Reasoning: combo decks tend to lose to aggro combat damage. Preventing all combat damage seems like an ideal stall method. You can still win with infinite Foam Swords or Spark, but your opponent may be much more limited in his options. With Grounding Totem on the table, Ossus can be a pain in the backside for even many of the tier 1 decks to deal with. The other, cheaper (cost 4), option instead of Ossus is of course
Archbishop Benedictus - which can be easier for you to dispose of before doing infinite combat damage; but who is also easier for the opponent to deal with.
Benefits: Combat damage prevention can keep your hero on the brink of death long enough for you to finish off with the combo. Especially useful is the opponent has already used up most of his destruction abilities to prevent your previous combo attempt.
3. Try to prevent dying to targeted damage to your hero. Since you're a Shaman, you should run some
Terror Pit Girdle. ASAP.
Reasoning: Myriam (with or without Inspire) and Belt of Blasting are dominating the whole metagame. You need a stratagem, and you do not have deck slots to be attacking Myriam or destroying BoB.
Benefits: Less dying. Armor 1 prevents Wand lock. Ossus + Girdle = semi-lockdown. Also, remember add some shadowmeld dudes into sideboard to increase the efficiency of the belt against specific matchups. Woodsie Leafsong seems like an ideal option, for you're not packing ability/equipment destruction MD.
4. Introduce more effective early game protection. Drop 4x Gladiator Lanthus and 4x Gladiator Keward. I would suggest replacing them with 4x Antikron the Unyielding and 4x Kulvo Jadefist, respectively.
Reasoning: Early game is very crucial for combo decks. If ignored in deck building, you will never live until late game and never pull off the combo.
Benefits: Lanthus does not work against untargetables and Keward has poor stats for his cost. This makes both of them really bad to play to an empty table in the opening turns, which seems to be their main function in the deck.
5. With less Arena allies and more non-Arena allies which are likely to survive until they can exhaust themselves to Path of Cenarius in the deck, the Ring of Blood could be changed into Gurubashi Arena to keep the combo somewhat reliable. Especially Antikron has been well utilized together with Masquerade Gown; the same trick can be applied with Gurubashi Arena and Path of Cenarius in this deck.
My "competitive" version of the decklist:
Hero: Zaritha
Allies (26)
4 Antikron the Unyielding
4 Mikael the Blunt
4 Gladiator Katianna
4 Kulvo Jadefist
2 Short John Mithril
2 Valeera Sanguinar
4 Krixel Pinchwhistle
2 Ossus the Ancient
Abilities (18)
4 Path of Cenarius
2 Spark
2 Recall from the Brink
2 Foam Sword Rack
4 Grounding Totem
4 Stoneclaw Totem
Equipment (4)
2 Terror Pit Girdle
2 Hand of Edward the Odd
Locations (6)
3 Gurubashi Arena
3 The Circle of Blood
Quests (10)
4 The Missing Diplomat
3 The Ring of Blood: The Final Challenge
3 Arena GrandmasterSideboard (10)
4 Woodsie Leafsong
2 Terror Pit Girdle
2 Ossus the Ancient
2 Rehgar Earthfury