Chao is better use for you. Later you can use reset emblems on him and use those emblems on Tiburtus. Or you might have 1010 Ranger emblems and not have to choose.
Kiril is a good choice for Wizard, he is my second after Proteus.
Personally I would do a second Proteus, and a third Proteus, before a first Merlin and all before a first Ameonna ( I abandoned leveling my Ameonna when I got Proteus and also when realized Tiburtus was the only Ramming Pulverizer in Ranger class).
Proteus is group mana control ( huge ), pure DOT bypasses reflect damage AND bypasses high defense stat. Anti-Guinevere hero, purple 4* Cheshire Cat is rumored to have pure DOT which will bypass Guinevere’s high defense stat.
Merlin is only single target and like Hansel ( fast mana speed) and Gretel ( average mana speed like Proteus & Merlin) trying to fill a Titan’s mana bar three times in 3 turns is impossible without luck. Proteus does not require refilling the enemy mana bar for maximum effect. In fact Proteus is effective even if you cannot fill the enemy mana bar while Merlin’s is less effective if the enemy mana bar is at zero and if you cannot fill the mana bar before the special expires.
Both Proteus & Merlin are purple, average mana speed and special lasts 3 turns.
Hansel ( fast mana speed with bonus special skill defense buff ) I might level before a second Proteus, but they are separate colors and I always level heroes with same color 1*-3* heroes.