Were generally talking about the cheapest versions of the cards found in Play boosters and Collector boosters, although some of the cards can only be found on the Retro bonus sheet (Ill mention this when relevant)
These each have unique cards and playstyles for players to experiment with
Kappa Cannoneer Kappa Cannoneer is a huge, mostly unblockable threat that you can cast for cheap if you have artifacts lying around
Second, thanks to Phyrexian Arena (and to a lesser extent, Dread Presence), we're likely to see a lot of our deck in any given game, so we'll draw into our one Josu Vess, Lich Knight or one Command the Dreadhorde eventually, and when we do there's a good chance it will close out the game
Pick a theme, then for every card you're considering, ask yourself, "does this card support my theme?" If not, then you can safely cut it
When Aragorn, King of Gondor enters the battlefield, you become the monarch