Adding fireballs or creepers to a team with friendly fire disabled still deal damage to its teammates.
Adding fireballs to team A
Adding creepers to team A
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Fireball and creeper does damage to team A
The creeper will not target the player itself but the explosion still harms its teammate. The fireball simply ignores it, deals damage regardless.
Steps to reproduce:
1.) Create a team and add yourself and the fireball to team.
2.) Disable friendly fire via team options.
3.) Hit fireball.
WAI. MC-46956