Introduction:
Lunalight is the Deck of Serena from the Fusion dimension in Arc-V. The archetype is composed entirely of Beast-Warriors, with all of them being DARK Attribute, except for the two Pendulum Monsters which are instead LIGHT.
With the new support from the OCG/TCG "Duelist's Advance" set, Lunalight has received a noticeable boost. Between one card combo starters, a powerful in-archetype boss monster, and even a way to search Loading... , these cards have completely redefined the identity of the deck. Compared to previous iterations, Lunalight is now innately a primarily going first combo deck, and much less reliant on outside cards to facilitate these combos.
What is sending a card by card effect?
The easier way to frame this question is perhaps in the reverse. What is sending a card for cost? In cards printed with Problem Solving Card Text, the section of a card's text that is regarded as a cost is usually located before the semicolon ;, but after the colon : (if there is one, with the text before the colon generally being information about activation conditions).
Importantly for Lunalight, the Fusion Summon performed by the effect of a card that initiates a Fusion Summon does itself count as a card effect. Therefore, cards like Loading... that send materials to the GY will allow activation of Lunalight monster effects that require being sent to the GY by an effect.
Core Cards
Lunalights:
Main Deck Monsters:
Lunalight Gold Leo
Gold Leo's first effect, on Summon, first searches for any "Lunalight" monster, and then discards a card. The notable property of this discard is that it happens after the search and discards as effect. Many of the other main deck Lunalight monsters have effects that activate only if sent to the GY by a card effect. This means Gold Leo has the ability to search a monster and then immediately discard it to activate its GY effect. Outside of that use, the discard can be any card from your hand, not specifically a "Lunalight" card, allowing you to discard something else if you want to keep the searched card in hand.
Gold Leo's second effect activates when a "Lunalight" monster is sent to the GY by any means, and adds that monster to your hand. One of the primary uses is that this allows Loading... who sends Lunalight monsters from the Deck to the GY for cost to essentially function as an additional searcher.
Lunalight Silver Hound
Silver Hound's primary GY effect activates upon being sent by effect, and Special Summons a "Lunalight" from the Deck, but locks you into summoning only "Lunalight" monsters from the Extra Deck while that Special Summoned monster remains on the field. Generally, due to the lack of "Lunalight" Link Monsters, removing the restriction means Fusion Summoning Loading... .
Lunalight Kaleido Chick
Kaleido Chick's first effect is where the card's complexity lies. On a soft once per turn, she can send a "Lunalight" monster from Deck or Extra Deck to the GY as cost in order to allow her name to that of the sent monster if she is used as Fusion Material. Starting from the beginning, this effect being a soft once per turn means you can resummon Kaleido Chick to use the effect to send specific Lunalight names later in the combo. Since the cards are sent as cost, they will not activate their effects if sent by effect, however in combination with Loading... , you can simply add whatever Kaleido Chick sent to your hand. Finally, the name change effect. Lunalight's Fusion Monsters are based around the idea of slowly climbing up from the humble Loading... to the mighty Loading... . However, going the normal way would be horribly expensive, so the archetype provides multiple ways to "cheat" your way to the end. Kaleido Chick is one of the cards that can facilitate this directly, but compared to two of the others, Kaleido Chick's name change will likely come up only in very strange game states. Interestingly, Kaleido Chick cannot send another copy of Kaleido Chick, likely because changing her name to the same thing is not a change.
Lunalight Yellow Marten
Her other effect, while in the hand or GY, she can return another face-up "Lunalight" card you control to the hand to Special Summon herself, but then banishes herself if she leaves the field. This effect is primarily intended to allow resetting your Pendulum Monster effects, however, in certain circumstances if quick Xyz Material is needed, returning to hand an active Loading... is also possible. Additionally, due to the way being on the field and leaving the field is treated, using Yellow Marten as Xyz Material means she no longer has to banish herself.
Lunalight Black Sheep
Lunalight Emerald Bird
Emerald Bird's other effect, if Normal or Special Summoned, she can send a "Lunalight" card from your hand to the GY as effect and then draws 1 card. This effect is difficult to make use of. Special Summoning a Lunalight without negating its effects does not happen often, having a card in hand worth sending at that moment is not guaranteed, and Normal Summoning her is also not a great choice.
Lunalight Tiger
Her other effect activates if she is destroyed, allowing you to Special Summon a "Lunalight" from GY without the restriction of negating it. Note that being a Pendulum Monster, Tiger will most likely move to the face-up Extra Deck after being destroyed.
Lunalight Wolf
Also, combined with Loading... 's Scale of 5, she makes the lower Scale allowing Pend Summons of Level 2 to 4 "Lunalight" Monsters (Wolf restricts you to Lunalights only).