There are ten mech lands, two for each basic land type: You can find the mech basic lands in traditional foil and non-foil in The Brothers' War Set and Draft Boosters
Cards that benefit in some way from challenging haven't been very good so far and this one also requires the additional requirement of being at a location
Super fun, but way too variable
I run both in my Mowu, Loyal Companion deck, and its reasonable for me to draw upwards of ten cards
Glistener Elf Our final Green card is this common, that costs one and is an Elf and Warrior with 1/1 body and infect
While it requires you to track and remember specific things each turn in order to resolve the trigger in the end step, it does remove the need to disrupt the middle of someones turn to announce triggers in the manner required by cards such as Rhystic Study or Smothering Tithe