sky striker booster box Yu-Gi-Oh Cards - Battles of Legend: Hero's Revenge YGOrganization | Deluxe Duel Set:

In those cases, you dont need to follow normal timing rules, but those effects will specifically say so

Oneiros, the Dream Mirror Erlking X LIGHT Level 10 [ Fairy / FusionEffect ] ATK 3000 DEF 3000 2 "Dream Mirror" monsters with different Attributes While face-up on the field, this card is also DARK-Attribute

This makes it easier for new players to build a balanced deck

Drawn from the god-filled skies of Theros, some cards, such as the cosmic soldier named Favored by Iroas, gain bonuses and new abilities whenever an enchantment or other constellation enters the field

So long as the card presents a consistent use case for one or two mana, then the more expensive door is easily justified as a situational or late game bonus