Dragonmaster Z wrote: This card cannot be Normal Summoned or Set. This card can only be Special Summoned by removing from play 1 LIGHT and 1 DARK monster in your Graveyard. Once during each of your turns, you can select and activate 1 of the following effects:
It never specifies WHERE it's to be summoned from. We assumed from the hand, but is it possible to activate the effect and summon him from anywhere else?
To answer your question, although others have done the same but didnt explained as to why is has to be done that way ( and no other possible ways ).
BLS is a semi-nomi monster. This term means that is has to succesfully special summoned via the criteria mentioned on the card itself ( in this case removing a light and dark monster from your grave from play ) before it can be special summoned via revival cards or monster effects.
Semi-Nomi monsters that are commonly played at this moment:
Chaos Sorcerer
Synchro Monsters ( unless if the card specifically specifies that it can only be synchro summoned )
XYZ monsters ( unless if the card specifiaclly specifies that it needs to be exceeded )
If you wish to learn more about the difference between semi-nomi and nomi monsters you can always hike to the realm of Yugiog wikia and read your information there.
Hope this helped you out, and I believe you answer has been answered beyond your need. So I guess this can be closed as well.