You can Ritual Summon this card with "Dark Dragon Ritual". At the start of the Damage Step, if this card attacks a Defense Position monster: Destroy that monster. You can Tribute this card; Special Summon 1 "Red-Eyes" monster from your hand or Deck, except "Red-Eyes B. Chick". You can only use this effect of "Paladin of Dark Dragon" once per turn.
Destroys opponent’s face-down defense position monster at the start of the Damage Step.
Can be tributed to Special Summon any “Red Eyes” monster from your Deck, except “Red Eyes B.Chick”
“Red Eyes” monster Special Summoned by this effect can attack during the turn it was Special Summoned.
Weak DEF stats susceptible to position switching plays.
Requires Ritual Summon to get this monster out.
You can also use Paladin of Dark Dragon’s effect to strategically destroy your opponent’s face-down monster without going through the whole Damage Step. You can tech Floodgate Trap Hole for this effect as well.
Dark Dragon Ritual card can also be banished from your Graveyard in order to add 1 Red Eyes Spell or Trap card from your Deck to your Hand.
Sonic Bird can search for Dark Dragon Ritual from your Deck to your hand, while Senju of Thousand Hands can search for Paladin of Dark Dragon from your Deck to your Hand.
Red Eyes Black Dragon and Red Eyes Zombie Dragon are the best options currently to be Special Summoned to the Field. Red Eyes Insight additionally helps you draw Red Eyes Spirit faster, while Red Eyes Spirit in turn is able to bring back your Red Eyes monster from the Graveyard to the Field.
Rituals now are bad, slow and costly, the only reason why CAs were played was because they search, recycle and gives you a free monster removal. With CA you didnt lost card advantage. In this case, you need. 1 ritual, 1 monster, dark paladin only to get one red eyes which do nothing. 3 cards for getting 1 2400 vanilla monster from your deck.
I could see this doing very well in standard DM format, but not the smaller format we use for Duel Links. When you have a 40 card deck, having the ability to search and special summon is powerful. When you have a 20 card deck... not so much.