TCG Rulings

• Discarding cards to the Graveyard is a cost.^[1]

• The effect of “Brionac, Dragon of the Ice Barrier” targets a number of cards equal to the number of cards that you discarded to the Graveyard.^[1]

• If you Synchro Summon “Brionac, Dragon of the Ice Barrier” using a monster with a mandatory effect like “Goblin Zombie” as one of the Synchro Material Monsters, when the Synchro Summon is successful the effect of that monster will activate automatically. You will not be able to activate the Ignition effect of Brionac before the mandatory effect of “Goblin Zombie.”^[1]

• If 1 or more of the targeted cards are removed from the field before the effect resolves, the rest will still be returned to the owner’s hand.^[1]

Mentions in Other Rulings

• Machina Fortress: When this card is targeted by an opponent’s Effect Monster’s effect, you look at the opponent’s hand and discard 1 card from it immediately before resolving the effect of the Effect Monster. For example, if “Machina Fortress” is targeted by your opponent’s “Brionac, Dragon of the Ice Barrier” you first decide whether or not you want to Chain any effects. Then, when you go to resolve the effect of Brionac, first look at your opponent’s hand and discard 1 card from it. Finally, resolve Brionac’s effect and return “Machina Fortress” to your hand.

• Supervise: If you send a monster equipped with “Supervise” to the Graveyard as a Synchro Material Monster for “Brionac, Dragon of the Ice Barrier,” the effect to Special Summon 1 Normal Monster will activate immediately after Brionac is Summoned. You will not be able to activate Brionac’s effect until the Chain resolves.

OCG Rulings

• Discarding cards is a cost to activate the effect, which targets an equal number of cards on the field.^[2]

• When "Brionac, Dragon of the Ice Barrier" activates its effect and targets multiple Spell/Trap Cards, if an effect is chained that removes one of the card targeted cards, then the remaining cards on the field are returned to the hand.^[3]

• You can activate the effect of "Brionac, Dragon of the Ice Barrier" by discarding Spell and Trap Cards even if the effect of "Dimensional Fissure" is active and removing from play all monsters to be sent to the Graveyard. However, if the effect of "Dimensional Fissure" is active, then you cannot discard monsters to the Graveyard since they would be removed from play instead of being sent to the Graveyard, so you cannot activate the effect of "Brionac, Dragon of the Ice Barrier" by discarding Monster Cards.^[4]

On Priority after it is Summoned

• Goblin Zombie: If "Sangan"/"Goblin Zombie"/etc are used for a Synchro Summon, then their effects are mandatory, and must activate as soon as the Synchro Summon is successful.^[5]
  • If "Goblin Zombie"/etc is used for the Synchro Summon" of "Brionac, Dragon of the Ice Barrier", then you cannot activate the Ignition Effect of "Brionac, Dragon of the Ice Barrier" before the effect of "Goblin Zombie"/etc activates. Moreover, you cannot activate the Ignition Effect of "Brionac, Dragon of the Ice Barrier" in chain to the effect of "Goblin Zombie"/etc.^[5]

• Supervise: If a Gemini Monster which is equipped with "Supervise" is used as a Synchro Material Monster for a Synchro Summon, then the mandatory effect of "Supervise" activates as soon as the Synchro Summon is successful.^[6]
  • If "Brionac, Dragon of the Ice Barrier" is Synchro Summoned, then you cannot activate the Ignition Effect of "Brionac, Dragon of the Ice Barrier" before the effect of "Supervise" activates. Also, you cannot activate the effect of "Brionac, Dragon of the Ice Barrier" in chain to the effect of "Supervise".^[6]

Mentions in Other Rulings

• Machina Fortress: If "Machina Fortress" is targeted by an opponent's Effect Monster's effect, then you check your opponent's hand and discard one card when the opponent's Effect Monster's effect resolves, before doing anything else.^[7]
  • Example: Your "Machina Fortress" is targeted by the effect of your opponent's "Brionac, Dragon of the Ice Barrier". When resolving the effect of "Brionac, Dragon of the Ice Barrier", first, apply the effect of "Machina Fortress" and discard one card from your opponent's hand. After that, "Machina Fortress" is returned to your hand by the effect of "Brionac, Dragon of the Ice Barrier".^[7]

• Machina Fortress: If multiple copies of "Machina Fortress" which are face-up on your field are targeted by a single effect, then you apply each copy's effect which discards one card from your opponent's hand. Thus, if you control multiple copies of "Machina Fortress" and they are all targeted by the effect of "Brionac, Dragon of the Ice Barrier", then when the effect resolves your opponent discards one card for each "Machina Fortress" which was targeted.^[8]

References

1. ↑ ^{1.0 1.1 1.2 1.3} Konami Gameplay FAQ: Hidden Arsenal – Card Rulings (Version 1.0)
2. ↑ Konami FAQ: Synchro Monster > Brionac, Dragon of the Ice Barrier
3. ↑ Konami FAQ: Does the effect of "Brionac, Dragon of the Ice Barrier" resolve when one of the targeted cards is not on the field?
4. ↑ Konami FAQ: If "Dimensional Fissure" is active, then can you discard a Spell or Trap Card as an activation cost for "Brionac, Dragon of the Ice Barrier"?
5. ↑ ^{5.0 5.1} Konami FAQ: When "Goblin Zombie" is used as a Synchro Material for "Brionac, Dragon of the Ice Barrier", can its Ignition Effect be activated at the time of its successful Synchro Summon?
6. ↑ ^{6.0 6.1} Konami FAQ: Can the Ignition Effect of "Brionac, Dragon of the Ice Barrier" be activated when one of the Synchro Material Monsters for the Synchro Summon is equipped with "Supervise"?
7. ↑ ^{7.0 7.1} Konami FAQ: Your opponent discards from his hand by the effect of "Machina Fortress" at what time?
8. ↑ Konami FAQ: If multiple copies of "Machina Fortress" are targeted, then how many cards are discarded from your opponent's hand?