Choose two —
• Destroy all artifacts.
• Destroy all enchantments.
• Destroy all creatures with converted mana cost 3 or less.
• Destroy all creatures with converted mana cost 4 or greater.
11/17/2017 Each of the chosen modes happens sequentially. If a permanent has an ability that triggers whenever it or another permanent is destroyed, it will see permanents destroyed at the same time as it or before it, but not permanents destroyed by later modes.
11/17/2017 If the first and third modes are chosen, an artifact creature with converted mana cost 3 or less will have to be regenerated twice to survive. This is because the modes happen sequentially, and the regeneration “shield” is used up by the first one. (A similar thing happens with most of the other combinations.)
11/17/2017 If a card is exiled “until” another permanent leaves the battlefield, the exiled card returns to the battlefield immediately after that permanent leaves the battlefield during Austere Command’s resolution, and it may be destroyed by a later mode.