Hidden in Snow

[Twan]

Hidden in Snow summon a tribe of "up to 25" unfrozen + a leader + up to 2 mages but it seems some "tribes" are really small : last time I had only the leader, 3 unfrozens + 3 unfrozen warriors and 0 mage, not a good deal for 55 gems.

I wonder if the effect is decreasing with use (it was my third hidden in snow in the same province in 3 turns, it may be logical if there are no unfrozen left to be raised), season based (spell casted in early winter) or 100% random ?

In all cases hidden in snow looks like a not very useful spell for the nations able to use it, except if you get an unfrozen mage with good earth magic (if you can cast hidden in snow, you already have water + death mages, and the units are inferior to the sea trolls you can have for the same price, especially when the number of trolls is guaranteed ; but hidden in snow remain a good spell to get mages having access to earth magic with a non earth nation).