by Boarass
When monsters with a certain ability make the game less fun, you have to remember that there are two possible causes of the problem:1. The ability is badly designed, in general
2. That monster is badly designed, in particular
For example, imagine there's a 3-fame orc that has 6 armor and deals 6 cold damage. That's freakin' stupid, but it doesn't mean that cold damage or 6 armor are bad abilities. They're just abilities that happen to be present on a stupidly designed monster.
With respect to arcane immunity, I'm inclined to think that #2 is the problem.
In Mage Knight, there are lots of times when you can get a reward that's disproportionately good relative to the challenge you have to overcome to achieve it. This is balanced by the fact that you don't know exactly what monster you'll be facing.
For example, killing a Medusa is pretty easy, and getting an artifact as a reward for doing so in a dungeon is fantastic. But you don't know that you're going to face a Medusa; you might hit a Gargoyle instead. It's a nice balance.
However, in the base game, there were certain "obvious" tactics that could conquer anything, thereby nullifying the balancing element of the disproportionate reward. For example, when fighting random purples, "Take the hit, attack, then heal" was incredibly good. Against browns, a fireball or snowstorm could kill literally anything. Concentration + Swiftness also killed every brown that you didn't want to be hit by; the two monsters it didn't kill have a rather tame attack. Against dragons, Expose + 7 more ranged attack could kill any dragon, guaranteed. And of course, "Cancel attack + do whatever" was effective against everything.
Was this bad for the game? I don't know, but it did make those tactics and abilities extremely good, because they let you eliminate uncertainty and get easy access to disproportionate rewards. Good or bad, one of the goals of the expansion was apparently to curb these tactics, because all of additions to the monster piles pretty flagrantly neuter every "golden key" tactic.
Sorcerers and Familiars are monsters you really don't want to be hit by. In the browns, Hydras and Manticores add elemental resistance, and all of the new monsters are impervious to Concentration + Swiftness. Of the 6 new dragons, 4 are impervious to Expose. And throughout, Arcane Immunity strips attack-canceling effects of their golden key status.
Having played the expansion several times now, I like this. I like that the new challenges reward players who are flexible, as opposed to players who merely happen to have picked up certain key cards, because I subjectively find flexibility more fun than hoping certain cards come up. "Be flexible" is an easier condition to satisfy than "have Expose."
Anyway, back to arcane immunity. I think the problem is just that Grim Legionnaires are a stupid monster, not that the ability is bad.
Sorcerers are tame. Determination + 1 card will block them, and 6 armor is fine on a 5 fame monster.
The Shadow looks awful on paper, but if you play against it, you'll see it's not really a problem. Yes, it's harder to kill than a Medusa, but it doesn't paralyze you, either. Its attack is a joke -- 4 damage is less than any other tan monster -- and as far as armor 8 is concerned, well, that's what you have to deal to the Gargoyle if you haven't picked up elemental damage. As a counterbalance, if you do block the shadow, you get 4 damage for free. Seems fine for how weakly it hits.
The Summoner Dragon is fine too. Fireball or Snowstorm will kill it, and as David pointed out, its attack won't usually be as devastating or difficult to block as the other dragons'.
The Legionnaire is the only rotten apple in the bunch, because unlike with the other arcane immune monsters, there aren't a variety of ways to handle it, and you sometimes CAN'T let it hit you.
Saying you haven't played the Volkare scenarios means you really can't have an informed opinion on this topic.
I disagree with this rude comment. The Legionnaire's presence is very relevant to the base game. If he pops up in the red city, your only options are "ridiculous quantity of ranged attack" or "ridiculous quantity of block." You CAN'T let it hit you, so if you didn't go whole hog on ranged attack, you're screwed and that's annoying.
Consider the Amotep Freezers in the blue city, which was formerly the champ of "Obnoxious city/monster" combos. But even there, you can deal 7 siege attack, or use Expose, or (ha!) stop them from attacking, or sacrifice a unit. By contrast, against the Legionnaire, the only thing you can do is Ranged Attack 11. That's it, or block a ridiculously high attack. Any option to handle 22 damage is prohibitively costly. Goodbye flexibility, and as was mentioned earlier, that's an annoying thing to face in a random draw x-1 hours into an x-hour game.