The Archer moves along the path and attacks all enemy units or structures except for traps. Traps are ignored and damage the Archer when it runs over them.
General Assessment[]
Archers are the second type of troops you obtain and the first ranged unit. As such they will quickly fill the second unit slot on attacks. They serve the role of a defensive ranged unit to snipe enemy units approaching from the next lane. They tend to be quickly outclassed by other units and replaced as early as with Paladins. Later in the game, the Archers become relevant again due to their added blunt damage after acquiring Elite status.
Defense[]
Early in the game Archers can be useful to attack opponents from an adjacent lane or behind a blockade, causing damage that cannot be easily retaliated. However, they are easily killed by other ranged units, and most spells can kill an Archer quickly. Because of their relatively low damage and range, experienced players can usually bait Archers in nearby lanes or behind barricades into a position where they can be attacked and overrun quickly before the Archers can do significant damage (i.e. use Call to move troops away from the Archer to force them to advance to a position where they can be attacked).
Attack[]
Archers, especially at the max level, are an excellent attacking Unit and despite all towers having a 50% resistance to piercing, fall within seconds when confronted by a group of 5-6 maxed out Archers. Even the Castle Gate falls within seconds to an onslaught by 7-8 max level Archers, and even quicker if the Hero uses his Scream effect to up the Archer's damage rate near the Castle Gate.
Below we have two pictures showcasing the outstanding offensive ability of level 10 Archers (without any boosts activated) taking down a level 11 Castle Gate within seconds without any help from the Hero whatsoever.
At a morale cost of 2, they are extremely quick to call and one can have a big group of them at any point in time. They are also highly effective against units. Units with a weakness to Piercing Damage like Ogres and Pyromancers last no more than 2 seconds when confronted by a group of maxed out Archers. Others without a major weakness to Piercing like Mummies, Werewolves also die very quickly. Often a group of Archers can kill the Werewolf even before it gets to bring out its Battlecry ability. The only shortcoming of the Archer is its lower range compared to other ranged units, which means the enemy ranged Unit will be able to attack the Archer a little before the Archer gets to attack it. This can be seen in a 1v1 battle between an Archer and an Arblaster where the latter starts firing before the Archer starts to shooting its first arrow. Also, the Archer is quickly affected by AoE type damage dealt with Mortars and Pyromancers. However, all of these shortcomings are rather easy to overcome by having a huge mass of Archers at once if your Hero uses his Heal spell or Shield with the Regeneration bonus to restore any lost health and to remove the status effects of Poison and Fire.
Archers vs. Arblasters[]
Since both are ranged units, doing piercing damage, Archers and Arblasters are very much alike and serve the same role. Both unit types have their advantages.
Archer
Arblaster
Range
Having a short-range allows him to kill and go foes more often than stopping by continuously because of the enemies who keep approaching his range area.
Arblasters can attack earlier and makes it a more formidable fighter in the lane to lane combat. A downside is that they won't move from their position until they kill all Units around them.
Damage
Archers can take advantage of their damage only with their Elite Boost which gives extra Blunt Damage to their primary damage.
While the Arblaster's rapid attack might look more impressive, it does a comparable amount of damage per second. In fact, at the time the Arblaster becomes available, it has exactly as much firepower as an Archer that has all available upgrades up to that point.
Survivability
Archer has no weakness to Poison Damage but he's resistant to Piercing Damage. It always depends on the situation in which a unit has higher survivability.
The Arblaster has an advantage in terms of hit points but is very susceptible to poison.
Morale
At half the morale cost, Archers are much cheaper to summon. During an attack, this means that there can be two Archers for every Arblaster. For defensive waves, this is only true until the eight slots are all filled.
Arblasters don't cost much in terms of Morale Points to use in offense but they might be redundant at the early stages of the game. More useful rather are if used in defense mainly when the Frenzy Frost Blaster War Boost is activated, which highly increases the survivability of the whole wave.
Conclusion: One Arblaster is usually far better than one Archer, which is why it should be preferred for defensive waves if morale allows it. Otherwise, both units have their advantages for offense and defense.
The Arblaster's main advantage is its high range, the Archer one is its low morale cost. However, 2 Archers are always better than one Arblaster. So it is recommended to use Archers for as long as the Hero doesn't have the high Leadership required to bring out a huge number of Arblasters.
In a 1v1 battle, the Arblaster would win but that can be considered an unfair match up because in a 1v1 the Arblaster gets to keep all of its advantages (like its superior range) over the Archer & the Archer loses its moral advantage over the Arblaster (for every Arblaster you can have double the number of Archers).
So a fair match-up would be 2 Archers (4 pts) vs 1 Arblaster (4 pts) in which case the Archer would be the clear winner.
Here is a test video showing different situations (1vs1, 1vs2) to see how to perform max Archer vs max Arblaster: ROYAL REVOLT 2 - ARBLASTER vs ARCHER (test) (by Flothaboss).