Percival is a special unit in Stronghold Legends and only available to those users who are currently playing as the Arthur faction. He is recruited from The Round Table, and costs 500 gold and 200 Honour. You can find out ways to generate Honour in the game here.
His general skills and abilities mirror that very much of a standard Knight. His attack strength is virtually identical to that of a Knight in standard combat as well- in straight out combat between Percival and a Knight, it's essentially the unit that strikes the first blow that will win.
By default, Percival will be mounted when you purchase him from The Round Table. You can dismount him from his horse by selecting him and then clicking on the "dismount" icon.
Once mounted on a horse, any enemy units must first kill the horse before they can attack Percival himself, so there are great advantages of doing so, besides Percival moving a lot faster. The horse alone takes 2 Crossbow bolts to kill.
If the Horse is killed or you dismount Percival, you can mount Percival on another horse, but must wait for a short "recharge" time before this button becomes available again. To do this, select Percival and then click on the "Mount horse" icon. Note that by mounting Percival, like any unit, it will cost 20 Honour. Once you have attempted to mount him, a horse will instantly appear and he will automatically be mounted.
You can only have one Percival unit at any time. If he is killed, you will instantly be able to purchase another Percival unit from The Round Table again. Like all ground units from The Round Table, Percival has a special power, in his case called The Holy Blast. This special power will create a large blast thrusting any enemy units away from you in the location where it is activated. This blast does not affect any friendly units in the vicinity it is triggered. Note that Percival must be close enough to the enemy units to use it.
You can activate this special power by left-clicking on the yellow hand icon on the right side of your screen, and right clicking on the map where to use it. It can only be used somewhere within Percival's range already, and once used, it will require a "recharge" time. During this, the green line around the outside of the yellow hand icon on your screen must reach all the way around to the start before it can be used again.
This icon is only available while Percival is alive, so if Percival dies or you have not yet recruited him, you must recruit another Percival from The Round Table again in order to use it. Only he has the ability to use this power.
However as Percival is so similar to a Knight, the same weaknesses also apply to him. Without use of his horse, he is a very slow moving unit. He can easily get overwhelmed by defence systems such as Burning Logs, Ballistae or pitch ditches. And he can also very easily be picked off by ranged or aerial units, frozen by Ice units and have his health sputtered away over time by persistent attacks or fire. This is primarily due to the fact he moves so slowly.
Percival will also struggle against units such as Frost Giants, even whilst mounted, simply because Frost Giants are so powerful and can cause an enormous amount of damage. It's therefore extremely important to protect him well to prevent this from happening, particularly if the enemy is playing as a different faction with access to more advanced units and magical powers, as most of these are not limited.
Tip: Percival's power is extremely useful, especially when uenemy units are closing in on your castle, or have created a breach in your wall and are trying to attack you. By using his special ability, you can thrust these units back delaying their assault and in the process killing many more of them.
Any units that are thrust into forests, buildings or water will die and be removed from the map, so this can help in more way than one. You can also use this special ability whilst sieging castles as well, knocking off enemy defenders from their walls and defences.
Defenders thrown off the highest towers very rarely survive or lost almost all their health. All this makes this power very useful to prepare an assault, prior to using Bedivere's Horn of Camelot.