We all know Skink priests have to use Law of heavens So is there a point to having the Slann take it aswell? If you already have 2 level 2 skinks with it?
As a general rule I wouldn't you already have access to the spells you need with the skinks. There are a few reasons you would want to take it. First if you are playing with Tettoeko then your slann will become much nastier. Secondly if you the arcane configuration from the engine it would make it so both your priests and the slann have an easier time casing their spells.
Generally, no. Heavens has been weakened a fair bit since last edition and really there are much better choices for what lore to take. It is a slight advantage having the engine boost both the slann and the priests, but not enough to make me want to give him heavens.
All comes down to personal choice. If you see a justifiable strategic reason behind taking yet another lore of the heavens wielder to the table then do so. If your question then becomes; is it stategically viable to do so? Then the answer is mostly likely no it is not. Heavens is an off/def split lore. Variety, as they say, is the spice of life. It also poses a challenge for your opponent as they have to decide which spells to counter, which to be aware of and act accordingly, ergo, more lores = a greater range of spells = a greater challenge for your opponent. -Eagle-
I'm actually really fond of Lore of Heavens, but I'd agree with the other posters. The other lores are almost always superior choices though. However, as was mentioned, fielding Tettoeko lends some definite weight to a Lore of Heavens Slann. Along with the better spells, also consider the lack of Magic Missiles in Lore of Heavens. That negates the Channeling skill. While Channeling isnt mind bogglingly good, it can be a really nice tool if you are going magic heavy. Any lore but Life and Heavens can use Channeling. One really nice application of it is Hunter's Spear from Lore of Beasts. If you can get a Skink Priest into flank line of sight(hello Cloak of Feathers), you can cast a bolt through a unit's files instead of ranks at a STR 6 hit with no armor save.