"Super Minion's big forehead isn't just for show: sniping enemy defenses from a safe distance is simply a brainy move! Especially when you've grown too big to avoid Seeking Air Mines."
Level 8 & 9
Summary
The Super Minion is a Super Troop based on the Minion. It can be unlocked by boosting the Minion when the Minion is at level 8 or higher.
Boosting the Minion requires 25,000 Dark Elixir or a Super Potion, and doing so allows the Minion to be boosted for 3 days. The level of Super Minion you obtain from the boost corresponds to the level of Minion you have.
The Super Minion is a much larger Minion who fires rockets from a long distance to attack. Its Long Shot ability enables it to fire its first five shots at a very long range. Unlike the regular Minion, the Super Minion can be detected and attacked by Seeking Air Mines.
Super Minions have no preferred target when attacking; they will simply attack the closest building. However, once they become aware of enemy Clan Castletroops, Heroes, or Skeleton Trap skeletons (either by being attacked themselves or by being near another friendly troop under attack), they will leave their previously targeted building and instead engage the enemy troops. Once all of the nearby enemy troops are defeated, the Super Minions will proceed to attack the nearest structure.
Offensive Strategy
Consider using a Rage Spell to maximize the amount of damage your Super Minions do with their long-distance attacks. With some precision, you can place a Rage Spell so that the Super Minions will be in its area of effect from a distance and up close, getting the most value out of it.
Their long-range attacks from their ability allow them to outrange any defenses with a range of 10 tiles or less. This includes Archer Towers, Air Defenses, multi-target Inferno Towers and the Town Hall's Giga weapons. Saving a few Super Minions (together with a Rage Spell to boost damage if required) to snipe or finish off an exposed Giga Tesla/Inferno can be a viable strategy.
Defensive Strategy
A Super Minion’s Long Shot ability, high damage per second, and flexibility to target both ground and air troops make it a useful defensive troop. If you combine Super Minions with shorter-range troops like Balloons or Dragons, attackers will not be able to catch both groups of defensive troops with a single Poison Spell without taking heavy damage from either group (or if that's possible, positioning the spell to hit both groups will be difficult).
For example, combining Super Minions with Headhunters in defense will be able to effectively shut down unprepared Queen walks or charges. Such a Queen walk/charge will need at least two spells to deal with both groups (e.g. Poison to slow down the Super Minions, and a Freeze Spell to stop the Headhunters from doing massive damage to the Queen).
Trivia
You can have a maximum of 25 Super Minions at one time in a complete set of fully upgraded Army Camps. This number increases to 28 if you include the 3 that can fit into a level 8 or higher Clan Castle. On the battlefield, you can clone an additional 6 Super Minions with three level 3 or higher Clone Spells.