Every deck needs a way to deal high amounts of focused damage in order to deal with high life enemy targets and for that task Svara has Ice Smiths.  They are very economically efficient. You are spending 1 magic to give Ice Golems a “virtual” +2 attack strength and Bear Cavalry a "virtual" +3 attack strength.  That is definitely great value for 1 magic.

However, the movement cost is not trivial at all and one of the main reasons they can be so hard to use well. Every one of Svara’s movements is incredibly precious.

With that said, don’t be afraid to summon Ice Smiths whenever you have a movement to spare, as once you get past the movement cost their efficiency is great.

Bear Cavalry are the best targets, however Ice Golems can be Ice Repaired and enhanced with Ollag. In addition to that there are many tricks available to Ice Golems that Bear Cavalry don’t have access to, so don’t be afraid to give Frost Axe to Ice Golems, even if in general Bear Cavalry gets more value out of them.

Outside of their Frost Axe ability, Ice Smiths are still useful units, a 0 cost 2/2 with no abilities is a very playable unit in Summoner Wars.  But the first time you move them, you boost them, and then they “threaten” to give Frost Axe to something, which will usually require some kind of response from the opponent.

Don’t be afraid to summon Ice Smiths just for their combat capabilities though.