So Dragons of Tarkir brings us Megamorph, proving to us that the creative team (or whoever's responsible for naming mechanics) is not below using mega_____.
let's help them out by mapping all the other mechanics then, shall we?
I'll start, feel free to contribute!
megahaste:
Rocket-Powered Turbo Slug gave us super haste, so you would expect megahaste to be faster than that. So -> "You may reveal this card from your opening hand. If you do, at the beginning of your first combat phase you may put it on the battlefield tapped and attacking. Return it to your hand at the end of your turn."
megaflying: "creatures with megaflying can only be blocked by creatures with megaflying or megareach."
(possibly with the added line of "if a creature with megaflying loses megaflying, sacrifice it")
megatrample: trample + "If this creature deals lethal damage to a planeswalker or player, you may assign any remaining damage to another target planeswalker or opponent."
megadeathtouch: "any amount of damage this deals to a creature is enough to exile it, and the damage can't be prevented. Players dealt damage by megadeathtouch die."
megavigilance: "this creature cannot ever be tapped"
megaflash: "you may play cards with megaflash even when you don't have priority"
megamorbid: "if a creature died this game, ...."
megabands with other megas: I think we're crossing into pokemon territory here...
megacipher: "still doesn't do anything"