Lightsworn are a series of monsters introduced in the "Light of Destruction" booster set, with extra support added in "The Duelist Genesis". Their "theme" is sending cards from the top of their owners deck to the grave to activate effects. "Wulf, Lightsworn Beast" is an example of a lightsworn card that's effect activates when it is sent from the deck to the graveyard, in this case, "Wulf is "Special Summoned" to the field.
Power: Lightsworns have decent atttack strengh, with "Wulf, Lightsworn Beast" being a 2100 atk monster that is special summoned. Also they have Judgement Dragon, a 3000 atk monster that, by paying 1000 life points, destroys all other cards on the field.
Draw: Lightsworns have "Solar Recharge", discard a lightsworn, draw 2 cards and then send the top 2 cards of your deck to the graveyard.
Drawbacks: In one word, decking out. A lightsworn duelist must be careful to win fast, or the milling abilities of the lightsworn turn full circle and you run out of cards in your deck.
Lightsworns are among one of the best decks in the current "Meta".
References: My own personal knowledge and www.yugioh.wikia.com