Going first, Bystials arent the best for starting or extending, since they provide a single body and require a resource in the GY, which they typically cannot supply on their own, and rely on other engines
The third most expensive pre-selling card from Tarkir: Dragonstorm is another throwback to a classic, iconic Planeswalker: Elspeth, Storm Slayer
Backup is a flexible ability as it has a dual function in making another creature larger and giving it a new ability, or just making the initial creature larger
A nightmare that the threat of 4000 hit points with resistance remains even if you don't put out monsters
Multiples of each card or both cards in tandem are even better
Greninja Another good card for a Water Deck is Greninja