Activate only while there is a Level 7 or higher "Arcana Force" monster in your Graveyard. You can send this face-up card, along with one face-up "The Material Lord" and "The Spiritual Lord" you control, to the Graveyard to Special Summon 1 "Arcana Force EX - The Light Ruler" from your hand, Deck, or Graveyard, ignoring the Summoning conditions.
It seems the "level 7 or higher Arcana Force monster" cannot be Light Ruler. Was able to successfully activate Sky Lord with "The Moon" in the graveyard, but not when Light Ruler is the Level 7 or higher monster.
Hopefully they fix that, because you can initiate the Sky Lord with Light Ruler, but you can't send it to the graveyard...
If you use The Spiritual Lord to add The Sky Lord by sending The Light Ruler, you can only use The Sky Lord to summon The Right Ruler from your hand or deck, unless you have The Moon in your GY then you can summon The Light Ruler from your GY