I like this card, it's smilar to fusion gate, but more specific in what it can doRemove from play, from your side of the field or your Graveyard, Fusion Material Monsters that are listed on a Dragon-Type Fusion Monster Card, and Special Summon that Fusion Monster from your Fusion Deck. (This Special Summon is treated as a Fusion Summon).
The best part is that it can use monsters in the graveyard or field (not hand though) to do the fusion!
You can use your Lord of D.+Flute of Summoning Dragon combo and not have to worry if Lord of D. dies before Divine Dragon Ragnarok comes around to fuse King Dragun
But the most potential this card has is to do 2 fusions of the same monster!
Say you use Polymerization to fuse 3 Blue-Eyes White Dragons into Blue-Eyes Ultimate Dragon, now use Dragon's Mirror to remove those three Dragons for another Blue-Eyes Ultimate!
That can be made to work with any Dragon type fusion
I use a Dragon deck myself, so this card is really handy, but I'm not sure exactly how useful dragon fusions are to everyone else...
Also, there's a similar card called Miracle Fusion (CRV-EN039) that works with Elemental Heroes, so the same can apply, but replacing monsters with E-Heroes and E-Hero fusions
3/5