Currently on my grind to legend this season for the first time so I don’t have too much knowledge for previous seasons. I’m currently very hardstuck in diamond 2 by mages constantly. I don’t think the class is very fair with its many infinite sources of recourses and OTK potential but that’s not what this is about. What’s the reasoning for spells not targeting taunt creatures? Everything else kinda follows the suite of you have to attack/get rid of taunt first with minions/weapons but spells don’t follow this? I feel like with Sif being able to make 2-1 cost spells 8+dmg I feel like spells not having priority like everything else with taunt is a bit much. It kinda feels like a mechanic that can’t properly scale with power creep. Maybe when spells couldn’t do this much is wasn’t a problem but idk. Is there a reason spells don’t follow this and what’s y’all opinion on this?
Because taunt says that attacks have to target taunt minions first, and spells aren’t attacks.
Should spells that are purely for attack/dmg reason be considered “attack spells”? I know it’s never gonna happen but I do wish “spells” had certain classifications that followed certain rules. Since there’s so many different kind of spells that do such powerful effects. I feel like this would kinda help a lot of problems I see people have on here with each class having some form of spell use being abused.
Should?
That’s a complicated word in game design.
All game design choices lead to outcomes, and whether the design choice is good or not depends on what outcomes you want to generate, how often, and how they feel to players when they happen. Some choices are the equivalent of axioms: you just decide that things will work a certain way, and your subsequent choices flow down consequences from that initial choice. It doesn’t necessarily mean that that choice is right or wrong, even when you eventually get down to an undesirable outcome.
Spells not being attacks is a choice, and they could choose a different definition of what “attack” means mechanically. But think about the other consequences of that choice. You dislike the outcome of being OTK’d by spells targeting your face from hand, but is it necessarily better to make it so that direct damage spells become effectively useless when faced with a huge board full of taunts?
We already have a lot of things that specifically affect minions, most notably other minions that can attack them. Spells provide a second, orthogonal approach to the game, where pushing your minions to dominate their minions isn’t the only approach to winning. I personally think that’s a good thing, because it risks the game being too boring to have only one approach to victory.
There was at least one minion that had the effect you want.
Like it said something on the line, if any other friendly character dmged by spell, this minion take the dmg insted.
I wouldn’t mind, if somekind of new keyword would be in play just like taunt is. Maybe not as much common as taunt, but still found on a decent number of minions that also would have other uses, just like taunt minions often do have other abilities.
Spellcatcher or somesuch 
It has been suggested before that minions should be able to “taunt” spells, but it has never happened. Obviously “taunt” is a keyword that specifically applies to attacks, not spells, so another keyword may be required.
The closest we got (IIRC) was a very old minion called Bolf Ramshield, who redirects any damage from your hero to itself. However, it wasn’t very good (even way back then) precisely because it didn’t have taunt, meaning minions could “trade” with it by hitting face, and not taking any damage.
The way to beat Sif mage is either to disrupt their hand, or to beat them before they can assemble the combo. If you’re playing pure paladin, you have no access to any card that can disrupt the opponent’s hand, so you have to be agrressive and finish them before that. However, Paladin has plenty of ways to win quickly, including anything that can use Crusader Aura.
Remember the rule of scissors/ paper/ hearthstone:
Aggro beats Combo
Combo beats Control
Control beats Aggro
Sif mage is definitely combo, so aggro should beat it.
I’ve advocated for this in the past.
I’d love to see some sort of spell taunt in the game.
FYI
We may have never had a “spell taunt” minion in the past but we’ve had a handful of tech cards that do it one way or another
As mentionned above there has been Sanctum Spellbender which redirects any spell targeted on a minion (but not a hero) to itself
But also Kobold Monk that makes your hero untargettable by spells and hero powers until you deal with it first
And some other examples that protect your minions until you kill one in particular