Castle of Dragon Souls

You can only activate the card "Castle of Dragon Souls" at any time except during the Damage Step.

The effect "You can only control 1 'Castle of Dragon Souls' face-up on your field" is an effect that does not start a Chain Link.

The effect "②: Once per turn: You can banish 1 Dragon monster from your GY, then target 1 face-up monster you control; it gains 700 ATK until the end of this turn" is an effect that creates a Chain Link. (When activating this effect, you banish 1 Dragon monster from your GY as a cost. This effect targets 1 face-up monster in your Monster Zone.)

If you activate the effect "it gains 700 ATK until the end of this turn" during the Damage Step, it must be activated between the start of the Damage Step and before damage calculation.

The effect "it gains 700 ATK until the end of this turn" can be activated in the same Chain Link as the activation of the card itself. (If you activate "Castle of Dragon Souls" during the Damage Step, you must activate its effect in the same Chain Link.)

The effect "③: When this face-up card is sent from the field to the GY: You can target 1 of your banished Dragon-Type monsters; Special Summon it" is an effect that activates in the GY and creates a Chain Link. (This effect targets 1 of your banished Dragon-Type monsters. It can also be activated during the Damage Step.)