The White Lions have served as the personal guard of the Phoenix King since the time of Caledor the First. White Lion regiments are often despatched to join the armies of Ulthuan during times of particular danger, tasked with protecting High Elf generals and mages, or bolstering the overall strength of the army. White Lions are renowned for their unflinching courage in the face of overwhelming odds and terrible horrors, protecting their charge whatever the foe and regardless of the danger to themselves.
↑Armour-Piercing: The damage of armour-piercing weapons mostly ignores the armour of the target, making them the ideal choice against heavily-armoured enemies. They are often heavier and attack at a slower rate though, making them less efficient against poorly-armoured targets.
↑Armoured: Armoured units can block damage from any source apart from Armour-Piercing damage.
↑Forest Strider: Specialists in forest warfare, this unit gains melee attack and defence advantages when fighting in forests.
↑Lion Cloak: White Lion fur is not merely a fashionable status symbol, it also provides protection against regular and magical missile attacks.
White Lions are not generally a bad unit early on, seeing as they provide the High Elves with an easily accessible source of armor piercing melee damage to counter enemy heavy infantry. Their cloak also gives them the equivalent of a bronze shield in missile resistance while they wield great weapons. Their missile resistance is better than shield notably, because it is not only forward facing as all shields in the game are.
However, as a campaign progresses, they are surpassed in every aspect of their role by Swordmasters of Hoeth and should ultimately be replaced by them in late game.
From a multiplayer perspective they are good armor piercing units if the High elves want to try and win the infantry fight rather than rely on their missiles or simply know they will be going against heavily armoured enemies (Dwarves/Warriors of Chaos).
Their martial prowess raises their melee defence, but once they drop below half health they are very vulnerable to attacks. Try to keep them healthy for as long as possible either through avoiding poke damage from harassing units or using healing magic to keep them above the threshold. If possible, fight with them in forests to get 20% bonuses to MA/MD. Hiding them in the forests on a flank just to get a rear charge would be good idea anyway.