I thought it would be a good idea to cover a card that has caused much confusion lately: Celri, Monk of Dark World.
Celri, Monk of Dark World
Fiend / EffectIf this card is discarded by a card effect from the hand to the Graveyard, you can Special Summon this card to your opponent's side of the field in face-up Defense Position. When this card is Special Summoned by the effect of a "Dark World" card, your opponent selects 1 card in their hand and discards it.
ATK 100 DEF 300
1.) How to trigger Dark World effects
DWs are very specific about how it triggers its effect (and yes, its effect is a trigger effect). DWs do not get their effects when sent to the graveyard. Cards like Hand Destruction will never meet the conditions for any of the DWs -- ever.
DWs do not get their effects when discarded by a cost. DWs say quite specifically that it must be discarded by an effect, therefor cards like Raigeki Break will never trigger a DW's effect. Bare that in mind when you consider running Trade-In, you will not get Grapha's destruction effect.
DWs only ever get their effects when discarded by card effects. Card Destruction and Morphing Jar are fine because they discard by effect.
2.) Who discards for Celri
This causes a lot of confusion. Basically, the player who does not control Celri is the one who discards. If it is special summoned to your opponent's side of the field, you discard. If it is special summoned to your side of the field by something like Gateway to Dark World, your opponent discards.
3.) Celri is mandatory
You don't get a choice when using Celri. If its discarded it will special summon and it will activate its effect. There's nothing that can be done about it bar negation.
4.) SEGOC makes DWs powerful
If Card Destruction is activated and you discard 2 Goldd, Wu-Lord of Dark World, after all links in the previous chain resolve, both Goldds start a new chain becoming CL1 and CL2. This means that only 1 can be hit by Solemn Warning or Royal Oppression, 1 will special summon successfully. Only the very last one in the chain link can ever be negated.
5.) Where do DWs activate
The effect of a DW monster activates in the Graveyard, not in the hand. Shadow-Imprisoning Mirror will shut down their effects.
6.) Bonus effects
The bonus effects do not start their own chains. They all happen as one chain. For example, if Goldd fails to revive itself, you don't get to destroy anything.
The bonus effects cause Bottomless Trap Hole and similar cards to miss the timing. If Goldd revives and then destroys a card, the timing is no longer correct and BTH cannot be activated.
7.) Inherent vs. Special Summon by effect
Grapha still needs its rulings confirmed, but the following rulings are correct.
Dark Worlds summon by effect. When they are discarded, after all previous chains resolve, they start their own chain. When each respective chain link resolves, the monster is summoned.
That means Thunder King Rai-Oh, Inverz Roach, Black Horn of Heaven and anything like that cannot stop the summon of a Dark World monster. Use this to your advantage.
8.) Which order
Say you activate Card Destruction. Both players have 1 Celri, 1 Goldd and 1 Sillva in hand. The link works like this.
(1) Your Celri.
(2) Your opponent's Celri.
(3) Either your Goldd or your Sillva, you get to choose.
(4) Either your Goldd or your Sillva, whichever is left.
(5) Your opponent's Goldd or Sillva, their choice.
(6) Your opponent's Goldd or Sillva, whichever is left.
Mandatory effects go first, so Celri must go first.
Turn player priority means that your discarded cards link first, then your opponent's. Therefor it starts with your Celri, then your opponent's Celri.
TPP then lets you choose which order you want to put Goldd or Sillva. Then your opponent gets to do the same.
Then the link resolves in reverse. After all the effects have been completed, the Celris will start a new chain becoming link 1 and link 2, both attempting to discard cards from the opposing player's hand.
It's a tad complicated, but you get used to it.
If you have any questions, leave them below.