Dont tell people they should play Demented Frostcaller it’s the exact opposite of what you want in a tempo deck, a 4 mana 2/4 is just bad and the effect is not even half as good as Flamewaker…
I’d say Spellslinger is your best bet but the card is kinda random (it has seen some play tho) and you lose a lot of synergy (which is one of the big reasons why you play tempo mage)

Of course you can get to legend with it, it’s most likely the best deck to do it right now x) Im on a 11 win streak and rank 2 right now, rushed from rank 23 (havent played for 2 months) to 2 in 3 days and rank 6-2 was mostly shaman since I need fast games to get to legend in time 😀