As a side note, Ill mention that a decade or more ago, folks were calling Commander (well, its name back then, Elder Dragon Highlander or EDH) the dollar rare format. People started scouring trade binders for the kinds of things that no one wanted to play in other formats, like Time Stretch
One of most powerful and intriguing cards is Seymour Flux which is a slightly more expensive Phyrexian Arena that is flexible because you don't have to pay the life
Build awesome Commander decks on a 20 tix budget
The only other removal spell Id say is essential in mono green is Song of the Dryads
Should You Double-Sleeve Your Commander Decks
Hand Counters A solid defensive tech option, OP13-043-otama is a 1-cost, non-searchable 2000 counter that brings valuable flexibility to the deck