On top of creating a 4/4 bear upon entering, The Earth King also provides a powerful land draw engine for large creature decks, allowing you to search for and play a tapped mana for each attacking creature with power 4 or greater
Its -1 ability also neutralizes a permanent for a turn cycle, giving you both disruption and stalling power
When Enduring Tenacity dies, if it was a creature, return it to the battlefield under its owners control
Krabs is Charix, Raging Isle
Remember that, prior to this set, Green was third in Haste and Black was second so riot would have worked very well in Rakdos
The life-to-mana conversion makes explosive turns possible, letting you chain demons onto the battlefield in a single push