Creeper Legions

Creeper Legions are groups of creepers that travel in a pack. A pack is 13-18 creepers and per pack there are 3 special creepers.
Difficulty
Creeper Legions prefer to stay in or near Castle Ruins, but aren't afraid of going up to 125 blocks away. They start spawning as soon as the player receives their first diamond tool in any way.
Special Creepers
Within every pack is a Creeper Leader, they command the Creepers with hisses. They do not attack until half of the Legion is defeated. They have double health and are faster than the player sprinting. They can explode without dying. They have a red banner as a cape.
With a 50% chance to spawn per legion, there is the Flaming Creeper. When they explode, 8 ghast fireballs shoot up in the air randomly and within the blast radius, everything catches on fire. They are shades of orange and yellow instead of green and lime.
With a 25% chance to spawn is the Thorned Creeper. They only explode when killed and they damage 3 hearts on contact as their main attack. They have cactus thorns on them.
With a 25% chance to spawn is the Tank Creeper. They can explode 2 times before the 3rd blast kills them. They have double health.
Finally, per creeper there is 15% chance the creeper in question is Supercharged.
The Legion in Battle
The Legion of Creepers cannot damage eachother with their explosions. The normal creepers will charge like normal while the Leader can do one of 3 things with the Specials. He can either let them charge, hold them back, or swap them with the normals to charge. Your best chance of winning is taking out the normal creepers, as hopefully they account for half or more of the legion. Then the Leader will begin his attack and taking him down will cause the Legion to disband and whichever creepers left to attack on their own behalf.