Paladin is a powerful hero with a toolkit centered around supporting your entire army by making it more durable.
In this article, we'll be taking a look at his strengths, weaknesses and some common misconceptions I've seen about the hero.
Let's start off by taking a look at the skills Paladin has in his kit. Holy Light is the main spell. The entire reason why you pick Paladin, actually. A nice and simple spell that helps you keep your army fit for fight. Paired with an Archmage or Bloodmage, you'll have enough mana to do a ton of healing throughout a fight.
On a hero like Blademaster, Divine Shield would, obviously, be absolutely nutty, but while still powerful, it's more reasonable on a support hero like Paladin. Divine Shield and the natural bulkiness makes Paladin quite durable even if he's out-leveled by opposing heroes or against a strong tier 3 army. While it's a strong and important spell, you won't need to skill it more than once. Reason being that you'll just need it to keep Paladin safe from a sudden attack, so the initial 15s is more than enough to get him to safety. Once in a safe position, your enemy will just shift focus anyway, so you'll not really need the added duration.
Devotion Aura is one of the lesser appreciated auras in the game. It's not bad per se, it's just... alright. On level 1 it gives 2 armor, which almost equals +10% EHP to the already boosted EHP from initial 5 armor, for Knights with no armor upgrades. That's actually pretty nifty, but since the priority of getting the aura is delayed for two reasons. (i) Paladin's other spells being vital (ii) the fact that it's not a proactive effect like attack damage, mana regeneration or movement speed.
The ultimate of Paladin, Resurrection, can be incredible. If you can, somehow, get him to level 6, chances are that you also have well-upgraded Knights in your army. Resurrecting 6 of those guys is easily a game changer. The problem is, that you'll rarely have enough mana for it, as the spell costs 200 mana, and if your Paladin still has that much mana after a fight, you could probably have avoided them dying in the first place.
With the above as reasoning, the typical skill path for Paladin goes as follows.
While rarely seen, there are two other iterations of the skill build. One to be used with Paladin first against Undead, where the focus is to harass Acolytes/Ghouls with Staff of Teleportation, Divine Shield and Holy Light. With this strategy, it's both valid to go for "normal" army with Knights/Flying Machines or Siege Engines. If you opt for the latter, you'll be better off not picking Resurrection on level 6 and instead fully upgrading Divine Shield.
The other iteration is used against Orc when you go for fast expo and mass air. This will often lead to a game where the Orc masses Troll Batriders, against which armor helps a lot. Getting Devotion Aura and Scroll of Protection minimizes their damage a lot. If you should achieve level 6 in an all-air game, your ultimate will be obsolete though, since air units leave no corpses when they die.
An obvious alternative, supporting hero is Goblin Alchemist. Especially considering how popular he currently is. So let's compare their two healing effects; Holy Light and Healing Spray. For the sake of it, I've made a comparison between the two spells. It's no wonder that Healing Spray heavily out-scales Holy Light, however, since Holy Light is single-target only.
Looking just at this comparison, Healing Spray seems much better than Holy Light, since you'll only need to heal three units for it to do more healing per mana point. What we are not considering however is that the abilities serve different purposes. Since the healing from Holy Light is instant and single-target, it works much better against focus-fire and burst damage. That makes it especially good for countering Undead who rely on bursting units down one-by-one.
Of course, there are other things to consider when choosing a hero. Since Paladin has Divine Shield, it's easier for him to survive in a tough situation, while Alchemist offers more damage through Acid Bomb.
Paladin and the former Paladin prodigy, Arthas aka Death Knight, have a similar kit. They both have a spell that heals friendly units, a spell that keeps themselves healthy, an aura and both their ultimates bring life back deceased units.
Though they have similarities, one is almost always used as a first hero, while the other almost only will see play as a third hero. I've seen newcomers use the fact that Paladin isn't being used as a first hero as an argument for why he should be buffed. This is a misconception I'd like to spend a few lines on, as I believe Paladin is in a good spot as is.
Throughout this article, I've already touched upon how Paladins kit works so well as a third hero, but there are three other important reasons as to why Death Knight is used as a first hero:
To sum it up: Paladin is intended to be a third hero and is a great one.
If you get a Paladin and a Staff of Sanctuary, your opponent will have a much harder time finishing off any of your Knights. With Archmage, Mountain King and Paladin you'll also have one of the game's strongest tri-hero combos. Archmage provides mana regeneration and sustained damage with his summons, Mountain King brings burst damage and crowd control, and, as the cherry on top, Paladin makes sure none of your units die. A fantastic combination.