They appear similar to the Giant Skeleton due to their underbite (but are totally different in size), and have the same diagonal scar as normal Skeletons, but have a few exceptions like wooden spears which Spear Goblins bear, wooden shields, and Dark Prince helmets. They are also a bit bigger than normal Skeletons.
Because of the Guards' low elixir cost, they are a low-risk, high-reward card. They can eliminate ground troops like groups of Skeletons and can distract air troops like Minions, making them a good defensive option.
No matter how much damage is inflicted onto the shield, the Guard behind it will remain intact, just like the Dark Prince. This means that not even a Sparky shot or Rocket can destroy a Guard while it still has its shield.
The Guards can be used effectively to counter a lone Sparky. With their shield, they can withstand a blow from the Sparky and destroy it before it shoots a second time.
Guards are an excellent counter to the Prince due to them being able to tank a charge and 5 more hits. In fact, they can counter the vast majority of single-target troops.
The Guards can be countered with Area Damage troops or buildings. The Fire Spirits and Bomber are most effective, but the Wizard or the Bomb Tower are also good (but expensive) options.
Fire Spirits will take out Guards completely for a positive elixir trade.
Ice Spirit can be used to counter them, freezing them and allowing your Crown Tower to finish them off.
The Log can make short work of the Guards since it knocks off the Guards' shields making them weak enough for the arena tower to finish off.
The Guards are a good alternative to Barbarians if the player needs to keep their deck cheap as they cost two less Elixir. The trade-off is that the Guards have all-around lower statistics except for speed.
Level 2 or higher Guards' shields can survive a tournament standard Zap.
Guards are great for defending against the Graveyard, since they are more durable than regular Skeletons and have a longer range, and their shields prevent them from being killed by a Fireball or Zap alone. For similar reasons, they are also effective at countering the Miner, capable of tanking multiple hits from him.
Guards are more effective at defending than attacking. It should be used to gain positive elixir trades and counter pushing. Sending them to push is usually not a good idea, due to them having relatively low attack speed and low speed. However, they can be effective with a glass-cannon like the Mini P.E.K.K.A.
Guards are terrible at assaulting a Crown Tower due to their low hitpoints and vulnerability to splash units. With that being said, they excel at forming a counter-push when they survive from a defense. When using them for a push, they are typically best used to tank for the main push. Vice versa, if your Guards are out of rotation, you can use other cards to defend an incoming push, and cycle to your Guards. Once the units are done defending, the Guards can be dropped in front of any residual units, resulting in a strong counter-push, as the Guards can collectively tank 12 shots from the arena tower.
When the Three Musketeers are coming to a Crown Tower without support, once the player's Crown Tower targets the Three Musketeers they can do a quick drop of Guards then Ice Spirit. The first guard will absorb the instant 3 burst shots from the Three Musketeers and then the Ice Spirit will freeze them for 1.5 seconds which is enough time for the 2 remaining guards and Crown Tower to finish off the remaining Musketeers.
Guards are actually able to attack from a very short range because of their spears, similar to the Prince. Because of this, they can poke at a distracted Valkyrie without taking any damage, setting you up for a counter-push.
The Guards are good at slowing down mini tanks and tanks, preferably the Prince and P.E.K.K.A., as they have to strike each Guard 2 times, which will allow you to build up elixir.