If more than one player discards a card with madness simultaneously, the player whose turn it is puts his or her madness abilities onto the stack first, then each other player does the same in turn order
If you doubt why playing spells at instant speed is crucial, try playing against this guy under its counter pillow strategy
Land Color tag templates(None) Scoured Barrens This land enters tapped
After that, you have a single Obstinate Baloth, which comes in a four mana, while everything else in the pack is three mana or less
If you have loads of draw or token generation then you can have this represent a one shot kill pretty well
As for Tribute to the World Tree, the card screams synergy in any Green-based deck that runs a bunch of creatures