U.A. Stadium

The effect "①: You can activate this effect when a 'U.A.' monster is Normal Summoned to your field; add 1 'U.A.' monster from your Deck to your hand" is an effect that creates a Chain Link. (It does not target.)

The effect "add 1 'U.A.' monster from your Deck to your hand" is an effect that can be activated when a monster with "U.A." in its name is Normal Summoned in face-up position to your Monster Zone. You cannot activate this effect if a monster is Set in face-down Defense Position.

The effect "Once per turn, if a 'U.A.' monster is Special Summoned to your field: Activate this effect. Monsters you control gain 500 ATK" creates a Chain Link. (This effect does not target. It can also be activated during the Damage Step.)

The effect "Monsters you control gain 500 ATK" is applied not only to the "U.A." monster that was Special Summoned to your Monster Zone at that time, but also to all other face-up monsters currently in your Monster Zones. (Monsters that are Summoned or otherwise placed on the field after this effect is applied do not gain ATK.)