It conflicts with the rule of cool, which is generally a "dumb" thing to do As for it adding "strategy". With only 1 available cast there isn't much of a choice. You just dump your mystic shield on whatever is most valuable and most likely to be focussed. Which means that 9 out of 10 times you'l cast it at the exact same unit as he's the core of your army and your tactics revolve around him and thus buffing him will nearly Always be the right choice. You simply can't afford to lose the core your strategy is build around as that'l most likely cost you the game. It's only once you have multiple spell-casts a choice can really be made as that second and third spell-cast can go to one of the important synergy units, or be used to buff up a fodder unit to be a more effective tar-pit. As for a bastilidon with mystic shield and summon starlight being silly to deal with in a thunderquake. If your opponent is stupid enough to focus the bastillidon instead of going for the supportive units or playing the objective he kind of deserves to lose... Also, spamming defensive spells is generally significantly less oppressive than offensive ones simply cuz your opponent's stuff isn't dead now so he can actually react and cuz sniping the wizards has a greater effect on the capabilities of the army as a whole. Sniping an offensive wizard just means there's less incoming damage, sniping a defensive one means killing the next thing is easier. And lastly, unless you're fielding Nagash or a coven of Slann you're unlikely to be casting more than 3-4 spells anyway, so it's not like it's viably possible to cover the entire army in mystic shields regardless. Which ultimatly makes defensive spamm far easier to deal with as there'l nearly Always be valuable targets left that aren't buffed. Now that isn't to say that there shouldn't be some rule in place to curb the spam. It's just that this rule is terrible and we should have a different one. For example what's been mentioned before about the casting value of a spell going up as you cast it multiple times in a single turn. Similarly there's no need for every single spell to do D3 mortal wounds. Fiddling with those values could easily alleviate the power of spam. As for prayers not being subject to it. That's what I meant with it being inconsistent. It'd be less severe but it doesn't really "solve" anything. It'd just be a bandaid solution for the bandaid solution. It just leads to situations where you get 3 wizards that all cast a differently named spell that does more or less the same for pretty much the same casting value. E.g. with a tzeentch army take a tzaangor shaman a magister and a random wizard. Now cast arcane bolt, boon of mutation and bolt of change, which have similar casting values (5, 7 & 7) and all deal D3 damage. There's not much difference with simply casting arcane bolt three times unless you have some spare reinforcement points to trigger the bonus effects of the "difficult" spells... Having said that, the spell lores are still worthwhile in their own right as they flesh out magic which is good. They just aren't a "real" solution for the rule of one nonsense.