Gemrazer I like the idea of a little curve here, mutating the 4/4 body onto a mana creature, like Birds of Paradise, in order to blow up the inevitable mana rock someone has dropped

Absolving Lammasu Aerith Gainsborough Ajani's Pridemate Ancestor Dragon Angel of Vitality Archway Angel Aunt May Beza, the Bounding Spring Bishop's Soldier Bounding Felidar Cat Collector Charming Prince City Pigeon Compassionate Healer Crowd of True Believers Curious Farm Animals Dazzling Angel Essence Channeler Exemplar of Light Featherbrained Filcher Felidar Savior Flight-Deck Coordinator Guarded Heir Haliya, Guided by Light Healer's Hawk Herald of Faith Hero in Training Hinterland Sanctifier Holy Cow Inspiring Overseer Kutzil's Flanker Leonardo, Cutting Edge Leonin Vanguard Lifecreed Duo Linden, the Steadfast Queen Lita, Little Orphan Amphibian Lyra Dawnbringer Market Gnome Minwu, White Mage Momo, Playful Pet Rabaroo Troop Regal Caracal Rosa, Resolute White Mage Sarn of the Silken Throne Soaring Sandwing South Pole Voyager Spider-UK Stone Docent Sun-Blessed Healer Twinblade Paladin Twinmaw Stormbrood Vanguard Seraph Wanderbrine Preacher Wax-Wane Witness Werefox Bodyguard Zora, Spider Fancier

For example, a 1/1 creature that enters under your control "with a +1/+1 counter on it" won't receive an additional +1/+1 counter
Jaws can be a win condition in combos that create and sacrifice artifacts indefinitely, like those involving Pitiless Plunderer
Retrieved May 27, 2009
If Behind the Mask causes a Vehicle to become an artifact creature, it doesn't count as "crewing" that Vehicle for any ability that would trigger off of a Vehicle becoming crewed