Firewand ego and tribolt wand r7 with casting speed 18+ (or r6, r7 beats ego in damage now) for firebolt. Having allegro accessories and/or vivace magic charging speed reforges will be a huge plus in damage. Then, besides fireball, most of the other skills may need reforges for them to be 'OP'. With Blaze 20 and maybe 500 MATK you can run alby advance hardmode (3rd floor + last rooms of 2nd) easily with puppet crisis and ice spear, so you can use this for other mobs as well-BFO also helps a lot with blaze 
. Ice Spear is such a nice skill when you have explosion radius reforge and attack range reforge, I can clear the lower level alban modes with such ease with it. Now lightning rod, such a great and fun skill, personally I feel you just need an upgraded s5/6 staff (with 400+ matk) to clear all SM modes (probably not all the mobs in Lord missions); with other non magic skills you can spam battle before tail 2 in a few minutes with just L-Rod. Hailstorm, is a fun skill, I wish it was as strong as lightning rod as it's not useful in a lot of situations; I can only see it when you're soloing a boss or can pin mobs to a wall. Meteor Strike, its a good 1-time skills every 15min(?), the title should be a must for mages, and its great boss demolisher! TIP: when you're in any mission that has the prompt: would you like to enter the room, and you have the option to press "ok", you can leave that prompt unanswered and load meteor before entering the room! Just press ok when meteor is ready to unleash!. So now, you can avoid aggro to load meteor . Almost forgot thunder, I'd just like to say, they should revamp this skill xD (also make it add int too, can always use more int!). Thunder is not a bad skill, the cast time is a long time and the mobs need to be grouped to use it the best. You can combine it with blaze, but you gotta know where the knock-back location is, that's why ice spear is always used in tandem with blaze, you should/will know where the kb will be.
Inspiration, snapcast, spellwalk, along with the other utility skills/masteries should be ranked up as well .
If you happen to run giragishy, mastering party healing (for title) will be useful in times your party doesn't do too well in the raid.
Savage Wands for Blaze (or combat wand) their damage multiplier is the highest among wands for blaze. Ice Wands are usually made for IS-Blaze combo. Staves in order of possible highest MATK: Celtic Druid Staff (12), Original Sin Staff (11), Celtic Guardian Staff (10), Hermit Staff (8). Personally, I like the Celtic Guardian Staff since you can also use party heal with it ! I suggest upgrading them for full magic attack, because, int is one of the most easiest stats to obtain and you can easily get more through choco-caters along with divine link. So going above the 1500 cap should be easy after like 5k + of ap? i don't remember ><.
Some more fun stuff: walking speed is great with magic! A S-Rank Wave Sweeper is a great item to have (especially for humans and in general) with demi-god, william mount, and other speed buffs, you can run around with spellwalk and fireball everything.Then you have the game breaking deer hide. Just have your deer sit on top of you while you cast magic (primarily fireball) toss the ball of fire and mount on your *crystal* deer and hide. As long as your deer does not engage in any combat, you'll be able to use it's deer hide-also with pet MP availability. Blaze is one of the few skills left that has an iframe, invincibility-frame: where the animation of the skill allows your character to be "invincible" (no mobs will be able to attack nor will their skills land on you); which is the moment you let go of the charge and it will last about 1s. If you're fire-bolting against any enemy that can teleport, try to stand against a wall so they don't teleport behind you.
So, firebolt may be your main go-to skill, but its pretty tiring just clicking it x[. Fireball before spawning monsters, snapcast duo fireballs too! Ice spear can save you from being raped (crowd control). The other bolt spells, ice bolt has that nice slow but i'd still prefer ice spear to control things, but if happen to not be holding a staff/ice wand at any troubling moment, ice bolt those mob/s away and prepare more skills! There are multitudes of combos you can use with other non-magic skills with magic. I'd like to input more, but nothing is coming to mind atm. I hope this helps! have fun~
Edit: I forgot about enchants.
There aren't actually a lot of great enchants for mages, the ones that are majorly impactful are the ones for wands/staves. You can look up magic attack modifiers on wiki to see what's best. Generally only the staff ones are the on you should go for which I believe are really high ranks 
Max damage enchants work with a lot of magic skills (some may need BFO for them to apply), so max damage enchants are the way to go for everything else. Of course those halloween accessories are strong too, but very pricey.
EDIT 2: When you're end game (magic) red special upgrade path will/should always beat blue. So you can start making r6/7 weapons as well! I wish I could say more on what stage this is (mainly how much magic attack), but I can't remember when or find the link on the math some meticulous people have posted x[.
EDIT 3: Here are some vids of people who use magic /iwishicouldrecordidlovetoshowsomecoolthings
Ice spear in alban
crisis+IS+Blaze AAHM
and of course the reliant DPS: 
fully buffed! le~firebolt
