Why are you into drain magic? I hate how you there are effectively three times dice are rolled before you have any benefits, first you have to cast it, then they get to dispell it and then they get to try to dispell it again in their command phase before it has any effect. A lvl 4 especially is very likely to dispell it, in my book it is just a bad spell and one of the main reason I mainly want to use Elementalism.
I think Ethereal on your Slann is going to be necessary once people wizen up about the rules. Often TG will have -1 to hit due to screening Skinks and Skinks of course have that natively. A Slann however is a large target, so how I understand it people can shoot the Slann, do not get the -1 to hit they would get on all our other targets of you screen well because he is a large target and get to shoot TG without any disadvantage (ason 2+s the hits get transferred to them). Him being ethereal makes him very safe and makes it impossible to abuse that (I think it works like this, early days though)
A few reasons why I like Drain magic
1- Outside of WE and HE, LM are the only ones with access to High Magic. Unless I am missing something. This means few armies have access to it.
2- Everything I've seen, people are planning on all bringing Level 4 mages. Sure a Level 4 can easily dispel a level 1 and 2. But since you have to better the result to dispel, a level 4 is parity with a level 3 to dispel, and will be less successful at dispelling other level 4 spells than they are at casting. So if I can just prevent them from casting to begin with, thats great.
3- Dispelling carries the risk of a miscast now. A double 1 isn't just a failure, but an outright miscast. So the less dispel attempts I make the better.
4- Its a remain in play spell. So if they don't dispel it initially, this means they risk a dispel miscast TWICE to get rid of it. Sure the second attempt it easier, but its still an opportunity to miscast.
5- Dispel scrolls are 20 points and not automatic.
SO, adding 2 to your opponent's requirements to cast essentially makes you feel like a Level 6 wizard dispelling their spells. But with no risk to miscast for you, just them. And it pretty much shuts down level 1 or 2 mages, and most bound spells, without you having to so much as lift a finger. Yes, there are multiple rolls before it really has an effect, but if it does take effect, its great. And if if doesn't, it still presented them with more opportunities to miscast than me.
I think Dwarves running heavy on the runic and TK will be particularly handled by it. Also if I can get my old blood on carno in to kill their level 4 (or 3) early to mid game, I can just cast this and ignore the level 1 and 2s late game.
As for the ethereal discussion, I know you already see the fact he is protected by LC, but I have had this conversation outside the forums a few times now, so just going to elaborate on it for everyone's education, because I think alot of people are mixing up what "troop type" is.
Lone Character (pg 206 BTB) offers more protection than ethereal and prevents this "Bypass" of shooting TG by targeting the Slann, since he can't be targeted anyways.
LC says same troop type i.e. "Infantry, cavalry". It does not specify Regular Infantry, Heavy Infantry etc. There are 5 troop types (p 188) and the flavours within each of those are "sub-categories". Additionally, Lone Character applies to "Infantry or Cavalry", not specifying the Sub-Category. the Slann and TG are the same Troop Type - Infantry. They are not the same Sub-Category. But that doesn't matter for Lone Character. This makes sense for the most part in the context of the other infantry types- IE a Heavy Infantry Lone Character within 3" of a Regular Infantry unit shouldn't be targetable. I get how logically this would be a stretch for say a swarm protecting a slann, but mechanically sometimes weird things happen. Also, the game is built around taking big points characters. Would be unfun if a 400 point Lord was killed by 80 points of archers every game.
Pg 188, BTB-
"There are five main categories of troop type, each of which is further divided into subcategories.
For example, particularly large infantry fall into the ‘monstrous infantry’
sub-category of infantry. In such cases, when the rules refer to ‘infantry’ models or
units, monstrous infantry must also follow those rules unless an exception is stated for
monstrous infantry."
Pg 206, BTB
"Any character whose troop type is ‘infantry’ or ‘cavalry’ and that has not joined a unit is
considered to be a ‘Lone character’."
Pg 206 BTB, Targeting Lone Characters
A Lone character cannot be targeted by enemy shooting or by enemy spells whilst it is
within 3" of a friendly unit (that is not itself fleeing) that contains five or more models of
the same troop type as the character (i.e., ‘infantry’ or ‘cavalry’), unless the Lone character
is the closest target.
Monstrous Infantry does not have any stipulations on it other than what units they can join/be joined by. But that is moot as the Slann has fly.
So the Slann is Monstrous Infantry, but that's just infantry as far as Lone Character is concerned, meaning as long as he is within 3" of ANY INFANTRY that is 5 or more models, he can't be targeted by shooting either. Unless he is the closest target. Large Target does not bypass Lone Character. Just means they always have LoS and he can't get cover. But that doesn't matter if he can't be targeted. FAQ also extends this to cannons unless he falls DIRECTLY under the hole.
So IMO, Ethereal is really only useful if your Infantry Blocks are just obliterated, or you plan to zoom your slann around the board with his fly ability, or you are super paranoid about super accurate cannons. But if you are keeping him 'bunkered' up in your battleline, he is safe. And with Fly, even if he his closest shielding unit is reduced to less than 5, you should easily be able march him away in your next turn. And as far as the magical attack protection, if I was an opponent and know the slann was ethereal, I'd just make sure to charge it with something with magical attacks. Easy to plan to counter it.