Commanders like Phenax, God of Deception fall in the first category, while commanders like Grolnok, the Omnivore, and Sidisi, Brood Tyrant fall in the second
They aren't a resource like mana or energy
There's a Shredder who gets +1/+1 counters whenever anything leaves the battlefield, and a Krang who looks great for a blue-based artifact deck
GoatBots When it comes to buying cards from bots, I usually prefer GoatBots because they have a webpage with all the prices of cards in tix
Nature's Lore With the various dual lands in cube this has always been significantly better than Rampant Growth, not just for the ability to fetch up non basics but also because it puts the land in as if you had laid it rather than the always tapping Rampant Growth
That minus to the toughness lets you destroy any creature on the battlefield so long as you have enough Squirrels out