If you didnt buy a preconstructed deck (or you want to upgrade your precon), you have two big options for how you build your deck in terms of what you buy
If, by some chance, it isn't included in the explore-themed Merfolk commander precon coming with Lost Caverns of Ixalan the price will likely spike some when the deck releases
Premium Protection: Designed with a sturdy zipper closure and durable PU material, this binder keeps your cards safe from dust, spills, and damage
As I often explain in my Budget Commander articles, every time I build a rough draft of a deck, I make sure I have a certain ratio of mana, interaction, card advantage, etc
each of these cards lets you find a card from your library and put it on top of the deck to be drawn next
Its effect, letting a player live beyond zero life by building up poison counters, is also original and widely liked