Servant of the Stinger is another creature with a very respectable body and a 2-drop your opponent will often want to spend removal on - which I see as a big upside
Other cards you could add are Thassa's Oracle, Bident of Thassa, Retreat to Coralhelm, maybe High Tide, Tidal Influence, Tidal Surge, Tidal Wave, or high-toughness Crabs like Ancient Crab to hold the fort while you mill
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Situation three - pile control vs
Because the resources are communal, you always weigh short-term gains against what you leave behind for your opponent
The Good Our new Goblin Heelcutter would maybe only be a sideboard card if it werent for the fact that it is very likely going to deal three unblocked damage every time it is cast