When it enters, creatures get -X/-X, which can wipe tokens or shrink larger threats into range
He then becomes a 6/4 that, every time he does damage to a player, lets you draw two cards and play two spells that cost six mana or less for free
A 3/7 Treefolk Shaman with vigilance and reach for six mana, whenever Colfenor or another creature under your control dies, you can return a creature from your graveyard to your hand as long as the returned card has lesser toughness
If a card says whenever you cast a spell or whenever you cast an artifact spell, your artifact counts
Heres another top-tier 3-MV mana rock, one that gives blue access to some coveted ramp, then becomes a draw-7 in just a few turn cycles
The story inside the book is pretty cool, with a showoff on a desert island, and it really conveys just how far obsession can push people (and alien symbiotes)