Blackcleave Goblin Blight Mamba Blighted Agent Blightsteel Colossus Blightwidow Burn the Impure Carrion Call Chained Throatseeker Contagious Nim Core Prowler Corpse Cur Corrupted Conscience Cystbearer Fallen Ferromancer Flensermite Flesh-Eater Imp Glistener Elf Glistening Oil Grafted Exoskeleton Hand of the Praetors Happy Dead Squirrel Ichor Rats Ichorclaw Myr Inkmoth Nexus Lost Leonin Melira, Sylvok Outcast Mindcrank Necropede Ogre Menial Pestilent Souleater Phyresis Phyrexian Crusader Phyrexian Digester Phyrexian Hydra Phyrexian Juggernaut Phyrexian Swarmlord Phyrexian Unlife Phyrexian Vatmother Plague Myr Plague Stinger Priests of Norn Putrefax Razor Swine Reaper of Sheoldred Rot Wolf Scourge Servant Septic Rats Shriek Raptor Skithiryx, the Blight Dragon Skithiryx, the Blight Dragon Spinebiter Tainted Strike Tangle Angler Tel-Jilad Fallen Tine Shrike Toxic Nim Trigon of Infestation Triumph of the Hordes Vector Asp Viral Drake Viridian Betrayers Viridian Corrupter Whispering Specter

Im personally a fan of turning it into Dragonlord Dromoka and unexpectedly shutting off my opponents interaction for the turn
I think there are a few reasons that it can be considered downright rude to play spells like this
(2009-10-01) The top card of your library isn't in your hand, so you can't suspend it, cycle it, discard it, or activate any of its activated abilities
This is why it isn't so good for three or more colour decks in cube
[17] A grey symbol with a star is considered colorless and can use any color Energy card