Even though we're all pretty familiar with all the troops and spells in the game, you may find some new or useful information from reading this. The attack and health ratings are based on how they stack up compared to all other troops in the game. They are not "official", but my personal ranking of the troops.
Troops
Barbarians
Attack: ★★☆☆☆
Health: ★★☆☆☆
Barbarians are a cheap, economical unit that's powerful in big numbers but vulnerable to wizard towers and mortars. They are good to use in loot raids, but not recommended for war. Their only good purposes in war are for luring clan castle troops and pulling them into different directions.
Archers
Attack: ★★☆☆☆
Health: ★☆☆☆☆
Archers are a cheap, economical unit that pairs well with barbarians or giants to help shield them from damage. Like barbarians, they are primarily a raiding troop and not a war troop, but they can be used for troop luring, funneling, or picking off lone builder huts in war. They can be used to kill enemy clan castle troops effectively by luring them out to a safe area, dropping a poison on them, and quickly encircling a large number of archers around the enemy's troops.
Giants
Attack: ★★☆☆☆
Health: ★★★★☆
Low damage, high health troops. Used to draw enemy fire while your stronger troops take down enemy buildings. Primarily used for loot raids, but can also be used in place of golems in war if you need to cut a small funnel and want to dedicate more of your troop space to offense. Giants can pair well with small groups of healers.
Goblins
Attack: ★★★☆☆
Health: ★☆☆☆☆
A raiding troop that targets the nearest collector, storage, or town hall and does double damage to it. Very squishy and easy to kill, but does incredible damage to collectors, storages, and town halls. Strictly a raiding troop. Some pro-Clashers will actually carry a small handful of goblins (less than 5) to help cleanup buildings after defenses have been taken down, because they deal such high damage to their target buildings. But other than that, goblins should not be used in any significant number in war.
Wallbreakers
Attack: ★☆☆☆☆
Health: ★☆☆☆☆
This unit only has one use, and that's to break walls. Most effectively used when dropped in pairs, as 2 wallbreakers can take down most walls. They can be killed in one shot by mortars though, so try to time your wallbreaker drops inbetween mortar fire. Do not carry too many wallbreakers, because they are a dispensable unit and they can take up quite a bit of space that could be better used towards offense. A good number to carry for each war attack is between 2 and 7.
Balloons
Attack: ★★★★★
Health: ★★☆☆☆
This unit can be viable at level 5 for TH8, but when it gets upgraded to level 6, there is an enormous jump in damage and health. Balloons are either used as a third-stage cleanup troop to help eliminate defenses after the core has been invaded and air defenses have been taken down, or they are paired with lava hounds to take down enemy bases. They are very slow but deal very high damage. Using rage or haste spells on balloons is highly recommended to compensate for their lack of speed.
Healers
Attack: ☆☆☆☆☆
Health: ★★★☆☆
Healers work best in groups, and I find a team of about 4 healers to be very effective at keeping a target alive. 1 or 2 healers on their own will have little effect in keeping units alive. Healers work best when they focus on the archer queen, teams of giants (10 or more), or on pekkas and valkyries. The healers main weakness is the air defense, but blowers can also interfere heavily with healers by making them temporarily stop healing their target, or having them change targets altogether. Healers are often used on archer queens in areas of enemy bases that are far from air defenses and blowers, where the archer queen can go on an invincible rampage, and the rest of the army is deployed once the archer queen has destroyed a sizable chunk of the base (this is called a "queen walk" attack). Placing a rage spell on healers will actually increase their healing power, so using rage on healers can help them keep the queen or other units alive during intense firefights.
Wizards
Attack: ★★★★★
Health: ★★☆☆☆
Very high damage but low health troop. Needs the protection of giants, golems, or other high health "tanks" to keep the wizards alive as they rain damage upon buildings. Very commonly used in war attacks to create funnels by destroying sections of the perimeter to guide your other troops into the core. Wizards are weak to splash damage from mortars and wizards towers, and giant bombs will kill them instantly. For this reason, it is very bad to clump up all your wizards together. Don't put all your eggs in one basket, always be sure to give your wizards a little bit of space.
Dragons
Attack: ★★★★☆
Health: ★★★☆☆
High damage, high health troop. An essential war troop at TH8. The only true weakness a dragon has is to air defense buildings, which can take down dragons very quickly. Most dragon attacks revolve around eliminating as many air defenses as possible, and deploying dragons en masse to sweep the base. Dragons see much less use in TH9 and above, but they make excellent defense troops in the clan castle at all levels.
Pekkas:
Attack: ★★★☆☆
Health: ★★★☆☆
A unit with a good balance of high damage and high health, commonly used in wars. They are immune to spring traps and are resistant against wizards towers and mortars. Their primary weakness is their slow movement speed and slow attack speed. Try to compensate for their slow attack speed by spacing out your pekkas, try your best not to have them target the same buildings.
Minions:
Attack: ★★★☆☆
Health: ★★☆☆☆
An air unit with relatively high damage output. Commonly used in loot raids or trophy raids (with balloons), but seldom used in war. Can be used in place of wizards in war to create funnels in areas with no defense against air troops.
Hogs:
Attack: ★★★★☆
Health: ★★★☆☆
A pretty powerful troop that specifically targets only defense buildings until they have all been destroyed. Hogs can be used as a third-stage cleanup troop, as a hit-squad to eliminate an air defense for dragon attacks, or can be used en masse as a war attack. Heals are essential to keeping hogs viable throughout the attack, so never attack without a good stock of heal spells. Hogs can be vaporized by two adjacent giant bombs (dgb: double giant bomb). DGBs will eliminate any hogs caught in the blast, even a heal spell cannot save them from this, so watch out for empty compartments that have enough space to potentially have a DGB.
Valkyries:
Attack: ★★★★★
Health: ★★☆☆☆
Like a deadly tornado, they move swiftly and unpredictably and leave everything in ruin in their wake. The latest update has made these arguably the best unit in the game. Their offense and ability to attack two buildings more than compensate for their moderately low health. Valkyries must be used in groups of at least 6 or more to be effective, 1 or 2 valkyries on their own will not do much at all. Unlike most other troops, you'll want to keep all your valkyries together, do not spread them apart.
Golems:
Attack: ★☆☆☆☆
Health: ★★★★★
The frontline tanks, these units have enormous health that will absorb enemy fire for a very long time so you can deploy your other troops to attack in safety. Golems are immune to spring traps, unlike giants, and will explode into smaller golems once destroyed, making golems superior to giants. The only drawbacks to the golem are its very low attack and very slow speed. They cannot be relied on to take down buildings, their only purpose is to draw enemy fire away from your more offense heavy troops. Golems are usually best deployed spread out rather than grouped together, so they can distract more enemy defenses.
Witches:
Attack: ★☆☆☆☆
Health: ★★☆☆☆
A very fragile troop that deals very low damage, the witch's power comes from summoning hordes of skeleton troops. Swarms of skeletons can deal lots of damage, and can be used to distract enemy defenses by overpowering them in number. Witches usually work best in groups, but don't keep them too close together, or else traps and splash damage from wizard towers and mortars will wipe your witches quickly. The latest update made it so that skeletons no longer trigger traps, and it used to be that the skeletons would run ahead of the witch and trigger giant bombs before the witch would reach them. With this new change, the witch is now much harder to keep alive, so this troop is now seldom used in the war community.
Lava Hound:
Attack: ★☆☆☆☆
Health: ★★★★★
Golems of the skies. These units will fly to the nearest air defense to distract it (and any other defenses along the way) so that your other air troops can be deployed in relative safety. Lava hounds have ridiculously low attack power (they deal less damage than a single archer!). But when they die, they explode into a group of lava pups, which are very similar in attack and health to minions. Lava hounds are usually paired with balloons to make a killer combo.
Spells
Lightning:
Lightning spells drop 6 lightning bolts in a semi-random pattern around the point you drop them, and they are best used when dropped on the very center of a building you are targeting. Lightning spells are usually used to destroy air defenses. You can use 3 lightning spells, or 2 lightning spells and an earthquake to destroy an air defense.
Heal:
A very powerful spell, heals can make your troops almost invincible while they are inside. Heals are best used on units with high attack but low health, like hogs, wizards, and valkyries. Be advised, troops that are being targeted by an inferno tower cannot be healed.
Rage:
This spell boosts the movement speed and damage of any troops inside. It is a very useful spell that can be used to enhance any attack. If your troops are having trouble getting through a wall, a rage spell can temporarily turn them into "wallbreakers" to bust through to where they need to go. Rage works best on valkyries and balloons, which will temporarily make groups of them into wrecking balls.
Jump:
This spell temporarily "erases" a small area of walls, so that your troops can move through a base much faster. Jump spells are best used on walls deep inside a base, wallbreakers are best used on walls around the perimeter. Jump spells can be used tactically to direct troops into the compartments you want, so think best about where you want to place your jump.
Freeze:
This spell is available at TH9, but it should only be used against TH10 bases. The freeze spell is only useful against inferno towers, so if you are up against a base without inferno towers, you're better off using a different spell other than freeze. Inferno towers work by dealing low, continuous damage and then increasing that damage exponentially over time. Using a freeze spell helps disrupt that increasing damage, forcing the inferno to start ramping up its damage again from scratch. It's best to drop freezes about 3-5 seconds after the enemy's inferno towers have started targeting your troops.
Poison:
This spell works much like an inferno tower. It deals very low damage to begin with, but the damage increases exponentially over time. Try to drop these on enemy troops as early as possible, so the poison spell has time to build up to full power. If you can predict where the enemy's clan castle troops will engage your own troops, you can drop your poison spell there early to build up damage faster. Keep in mind, enemy troops in a poison spell will run away if there are no other troops on the battlefield. Also, poison spells do NOT stack on top of each other. Only drop them one at a time if you have 2 poisons.
Earthquake:
This spell reduces the health of all buildings (except storages) in a small area by a certain percentage. This spell is best used against buildings with very high hitpoints, like townhalls, clan castles, xbows, and inferno towers. If those buildings are clumped together, dropping an earthquake on them will help your troops to tear them down faster. 4 earthquakes of any level will destroy any enemy walls caught in the area. Earthquakes cover a larger area than jump spells and will destroy the walls permanently, so sometimes it's better to use 4 earthquakes over a jump spell.
Haste:
This spell increases the movement speed of any troops in it. It's like a rage spell, but it does not increase troop damage, just speed. In my experience, I have found haste spells to only be effective on balloons. So unless you are using balloons, it's not recommended to use this spell for your attacks.
