Confusion in the Ranks
Enchantment
Whenever an artifact, creature, or enchantment enters, its controller chooses target permanent another player controls that shares a card type with it. Exchange control of those permanents.
Ron Spencer
Mirrodin (MRD)
• #87Rulings
Confusion in the Ranks triggers on itself entering. If an opponent controls an enchantment, exchange Confusion in the Ranks for that enchantment.
(wotc • 2004-12-01)
The permanents are exchanged only if they're both on the battlefield when the ability resolves.
(wotc • 2004-12-01)
The permanents have to share a permanent type both when the target is chosen and when the ability resolves.
(wotc • 2004-12-01)
Even though Confusion in the Ranks triggers only when an artifact, creature, or enchantment enters, the ability can target a land if the permanent entering is an artifact land.
(wotc • 2004-12-01)
The exchange isn't optional. If there is a legal choice, you must make one.
(wotc • 2004-10-04)
Rulings
Confusion in the Ranks triggers on itself entering. If an opponent controls an enchantment, exchange Confusion in the Ranks for that enchantment.
(wotc • 2004-12-01)
The permanents are exchanged only if they're both on the battlefield when the ability resolves.
(wotc • 2004-12-01)
The permanents have to share a permanent type both when the target is chosen and when the ability resolves.
(wotc • 2004-12-01)
Even though Confusion in the Ranks triggers only when an artifact, creature, or enchantment enters, the ability can target a land if the permanent entering is an artifact land.
(wotc • 2004-12-01)
The exchange isn't optional. If there is a legal choice, you must make one.
(wotc • 2004-10-04)