Rulings

• 2004-12-01
  You no longer need four distinct targets for Decimate. If the spell or ability uses the word target in multiple places, the same object or player can be chosen once for each instance of the word “target.” For example, you could choose Tree of Tales for both the artifact and the land. You still need a legal target enchantment and creature as well.
• 2022-12-08
  You must choose a legal target for each target required by Decimate. However, if a permanent has multiple card types, it may be chosen as the target for more than one instance of the word “target.” For example, you could cast Decimate targeting an artifact creature, an enchantment, and a land.
• 2022-12-08
  You must choose a legal target for each target required by Decimate. However, if a permanent has multiple card types, it may be chosen as the target for more than one instance of the word "target." For example, you could cast Decimate targeting an artifact creature, an enchantment, and a land.