- Lightning Vortex wrote:
- Discard 1 card. Destroy all face-up monsters your opponent controls.
- Monster Reincarnation wrote:
- Discard 1 card. Add 1 Monster Card from your Graveyard to your hand.
As you see in examples, cost effects have a meaning like do something to active this effect.
There is not a shape line at the side of non-cost effects for Dark World. I mean you can't discriminate non-cost effects for Dark Worlds but you can take out cost ones because their effects are more shape about this ignition. There is a good list of them in YGO wikia:
- Card Destruction
- Clear Vice Dragon
- Dangerous Machine Type-6
- Dark Deal
- Dragged Down into the Grave
- Drill Warrior
- Fabled Raven
- Fine
- Into the Void
- Mirage of Nightmare
- Morphing Jar
- Rigorous Reaver
- The Cheerful Coffin
I also want to inform this, "cost" word is not in usage anymore. Because some monster effects don't have a cost but same goes for them. TCG uses "Ignition Effect" now. You have to ignite something for the effect.