I use it in a psychic deck, it's a good trump card option for a duel that drags on. if I draw early I normally bait the opponent to destroy/banish it. Only gotten to legend rank so far though on this deck so make of that what you will.
Deck Destruction decks in general are a great counter to Lightsworn, since good Lightsworn decks already get rid of 70% of their deck in the first few turns.
There are only 6 spaces in DL which means you have to have all other spaces filled in order to use this card. If you are in that position, then that probably means you are already winning.
You don't even need to test it actually, since it says "whose combined Levels are double the revealed monster's"
It never says "double or more", just "double. So of course having 2 Level 6 won't work to summon a Level 5 one.