If a creature with banding attacks, it can team up with any number of other attacking creatures with banding (and up to one nonbanding creature) and attack as a unit called a “band.” The band can be blocked by any creature that could block a single creature in the band. Blocking any creature in a band blocks the entire band. If a creature with banding is blocked, the attacking player chooses how the blockers’ damage is assigned.

A maximum of one nonbanding creature can join an attacking band no matter how many creatures with banding are in it.

Creatures in the same band must all attack the same player, planeswalker, or battle.

If a creature in combat has banding, its controller assigns damage for creatures blocking or blocked by it.

Chatzuk’s second ability doesn’t change the mana cost or mana value of any spell. It changes only the total cost you pay to cast spells.

Chatzuk’s second ability can’t reduce the amount of colored mana you pay for a spell. It reduces only the generic mana component of that spell’s cost.

Playtest cards aren’t legal for play in any tournament format other than Mystery Booster Limited formats. On the other hand, we expect they will spice up a wide variety of non-tournament games (as long as everyone’s on the same page about using them!).

Playtest cards use a modified version of game symbols, such as {T} and {W}. These modified symbols should be treated as the standard symbols during play.

For many playtest cards, you’ll need to make a generous assumption that basic game rules would be updated to allow them to work. The Mystery Booster 2 Playtest Card Notes section (reproduced here in individual Gatherer rulings) provides guidance for fitting these cards into the existing rules structure.