1. Non-creatures with the same or higher CMC than the band leader.
2. Double-sided cards.
In addition, while the flavor text of all creatures is still valid when a card is not in the band, while in the band all abilities are not used.
For the current standard format (ISD Block, M13, RTR set), here are some examples.
The highest possible CMC band in black is Terrus Wurm.
A + band member could be:
With a +8 ability, this band could use the -14 ability (this band deals 10 life to player or creature) second turn after coming into play. And three very useful band members could be:
And because the band works like a planeswalker, any enchantment-aura in a band cannot be a target of spells or abilities.
Here is a green band.
Here is a + band member (its red ability cannot be used when its in the band):
And here are three candidate band members:
Here is a good band member:
And here is a good + member (at +4):
Here are two other band members to complete the band.
Here is a blue band. This band leader would be a -10 loyalty.
Any member of the band with flavor text "when card dies" resolves as written when the band dies. Here is a + member (at +3):
And the three "regular" band members.
Here is a white band. This band leader has a -10 loyalty for 5 life.
Here is a regular band member. Any ability is not used while the card is in the band. For example, you can trigger a 1 mana ability for Burden of Guilt, but not when it is in a band.
Any one of these three cards can be the + member. The Fateful ability is null while Gather the Townsfolk is in a band.
No Flashback for Ray of Revelation while it is in a band.
