i have leveled Zagrog, Khagan and Azlar costume to 3/70.
After testing them a while at that level, none of these three seem to be able to join my standard 4+1 Red war/raiding team, which currently consists of the follwoing members:
Elisabeth (85/20)
Ferant (75/20)
Guardian Falcon (75/20)
Boldtusk (75/20)
some different colored healer
Further i own
Reuben (4/80)
Gormek, Boldtusk, Sumle, Kelile (4/70)
Elena (1/1)
Since I’m already waiting over a year for someone better and do not want to wait any longer, one of the three now gets the rings.
Azlar costume appears to me as the best choice, because in his costume he is somehow tanky (paladin) and does a lot of damage.
Khagan seems to be the usefull too (+manareg and +defense), but looks a step behind Azlar to me.
Both are strong options in very fast tournaments and wars and i guess will even replace the falcon or Ferant then.
Zagrog, well - he is not bad, but looks very niche.
Yes, usefull against counterattack teams, even against nasty Alfrike if i undertand his passive correctly, but he only hits mediocre for medium speed in my opinion.
If you are looking a hero specifically for very fast wars/ tournaments, then Azlar Costume is for sure the best choice.
Otherwise, because of the speed, I would go with Zagrog. He hits hard and can work great with Falcon, Ferant and Gormek (not Boldtusk). I don’t consider him niche, I think he is more versatile than Azlar. He hits very hard and his natural immunity to mana ailments make him very valuable. And his hit is not mediocre at all - 420% + minor to opponents is higher than Master Lepus who is considered a very hard hitter. I was planning to maxing him until I got Lewena.
If it was Khagan costume, I would vote for it in a heartbeat. Especially with LB and emblems. Zagrog looks the best to me out of three because I find azlar weak. If I see azlar on defence, I attack no matter who else is on team
ehm costume azlar can deal 410 damage to 3 heros + 600 dmg dot.
i would rank them as follows,
Costume Azlar > Zagrog > Khagan (for offense)
i have Costume Azlar maxed and limit broken and currently leveling Zagrog, not sure if to up him or not but his passive mana ailment resistence and attack debuff resistence are vey good agaisnt alot of heros and his damage is decent if def down is applied.
keep in mind he is one down of the few heros that can bypass damage reduction buffs (sif, wolfgang)
for defense Zagrog could be better than Azlar, Khagan due to speed.
Zagrog has higher stats and is average and almost the same dmg. Zagrog speeds up if bypassing buff which makes him fast. Azlar is just weak. I had a raid just few minutes ago. Filled c azlar to fire first and it was weak. On the other hand, if I see Khagan with costume bonus on raid, I take care he does not fire because it often means gg
I didn’t meant to compare them neither said Zag is weak, I’ve shared my experience with C. Azlar, who is very effective and I’m glad I have him as my kitty. In very fast mode, when he is combed with a def down and an atk up, only few can survive if I fire him 2 times in a time space of 2 turns.
Even I own 2x Zag I won’t max him because I plan to max and emblem a second C. Marjana. So I can’t really say much about him. I’ve tested him in beta but the didn’t surprised me that much, even I consider him a usable and above average hero.
C. Azlar is great-you won’t be disappointed. His tile damage alone makes him worth using for Titans but he can clean house in wars/raids. I regularly clear 2-3 heroes with one shot with him (I usually run 3-2 and pair him with a sniper to knock opponents to below 50.)
I love love love costumed Azlar I´d max him out straight away if I had him, no question about that! (But, mmmmmaaaaybe it´s because, he also reminds me of my dog, too… )
I´d max him out straight away if I had him, no question about that! 
(But, mmmmmaaaaybe it´s because, he also reminds me of my dog, too… 
)