My humble opinion base on the deck you posted.
Firstly, if you can afford an epic, get the 3rd Makantor. (or may be you already have one and it just doesn’t show up)
If you can afford some rares, 3 Thumping wave (- 2 Repulsor beasts and the last slot). Both are 3 mana removal but TW is much better especially with Vaath and it can also be a good finisher with all those rush minions you have here.
For the buff cards, may be run just 2 or 3 Diretide frenzy? (Cause it seems to me like you want to use that Wings of paradise+ Frenzy combo XD) but no more than that since you have no card draw and buff spells in Magmar run your hand dry really fast.
Or you can drop the Wings+Frenzy combo altogether and go for solid Greater fortitude and some Sojourners instead. I think this is up to your preference. I myself find Frenzy a bit harder to use (it needs the right opportunity to arise) so it’s quite situational. GF is simpler.
I feel like I’ll need some kind of card draw if I’m to run a lot of buffs in Magmar. Our buff doesn’t give card draw T^T (Razor skin is not a kind of draw you want unless you go flooding the board)
You also have quite a lot of 2 cost cards which makes you run out even quicker if game drags on. So having a way to refill is very nice. (If opponent wipe the board after you commit, you can still come back)
Also, 3 Elucidator may be a bit much but it’s optional. May be 2 Primus and 2 Elu?
Egg morph is slower but more reliable than Natural selection. I would personally run 2 NS and 3 EM.
Lastly, if there is still space left, go Healing mystic (very good on Vaath as you kill minions and heal back it’s almost like a removal !)