So many awesome Dragons these days are legendary, so getting to put them in your deck and possibly make copies is amazing
At each of your upkeeps, you can exile cards from your opponent's library based on the number of mercenaries you control and play them until the end of turn
Fulminator Mage Fulminator Mage has seen some Modern/Legacy play as targeted hate against good nonbasic lands
These abilities can only be used at Sorcery speed, but because the active player gets priority after a card enters the battlefield - you're pretty much guaranteed to be able to use of them before anyone can stop you
When you cast the spell, you pay an amount of mana according to which tier you would like to cast the spell at
The +2/+0 buff is useful because there are many scenes where multiple mice are lined up, and you can trigger Valiant simultaneously, or use it on two [Diverse Mice] created with offspring to deal 12 damage