It's as simple as purple and gold.

[Lunar Origins]

Royal Sentry

[ DARK / Level 4 ]

[ Warrior /  Effect ]

If this card is not being revealed in your hand:  You can reveal this card in your hand during the Battle Phase:  This card can declare an attack (from your hand).  This card remains revealed after being revealed by its own effect.  When this revealed card in your hand leaves your hand:  Send 1 "Royal" monster from your Deck to the Graveyard.

[ ATK: 1400 / DEF: 1400 ]

 

Royal Paladin

[ LIGHT / Level 6 ]

[ Warrior / Effect ]

If this card is not being revealed in your hand:  You can reveal this card in your hand during the Battle Phase:  This card can declare an attack (from your hand).  This card remains revealed after being revealed by its own effect.  When this revealed card in your hand is Normal Summoned:  You can add 1 Level 4 or lower "Royal" monster from your Deck to your hand.

[ ATK: 1600 / DEF: 1200 ]

 

Royal Guard

[ DARK / Level 4 ]

[ Warrior / Effect ]

If this card is not being revealed in your hand:  You can reveal this card in your hand during the Battle Phase:  This card can declare an attack (from your hand).  This card remains revealed after being revealed by its own effect.  When this revealed card in your hand is discarded:  You can add 1 "Royal" monster from your Graveyard to your hand.  That monster is revealed in your hand until the End Phase of your turn.

[ ATK: 1200 / DEF: 1400 ]

 

Royal Assassin

[ LIGHT / Level 7 ]

[ Warrior / Effect ]

If this card is not being revealed in your hand:  You can reveal this card in your hand during the Battle Phase:  This card can declare an attack (from your hand).  This card remains revealed after being revealed by its own effect.  When this card inflicts Battle Damage to your opponent:  You can discard 1 card, then draw 1 card.  If the card drawn by this card's effect is a "Royal" monster: Draw 1 more card, then end the Battle Phase.

[ ATK: 1300 / DEF: 2000 ]

 

[hr]

 

Royal Palace

[ Spell / Continuous ]

During your End Phase:  You can discard all of the cards in your hand; Add 2 "Royal" monsters from your Graveyard to your hand. Those cards are revealed until your next Main Phase 2.

 

Reinforcements of the Palace

[ Spell / Quickplay ]

Normal Summon 1 "Royal" monster from your Graveyard.