1. Perna: Fire Phoenix
I speak from personal experience when I say that the fire phoenix is one of the best creatures to have on your team in Summoner's War. Yesterday, I was actually lucky enough to have summoned one from a mystical scroll I got from an achievement and am very satisfied with the results so far.
The first thing I did after doing a bit of research was equip her with four fatal runes, most of which primarily came with base attack bonuses. That extra 35% bonus to attack really makes a difference.
Next, I gave her two endure runes, thinking that the 20% resistance would make her health last longer.
Once I did that, she was able to solo all of Garen Forest (Normal Mode) by herself. Not only that, but her passive is extremely durable when it comes to dungeons of any sort.
Her passive can revive her or an ally member every twelve turns and it heals your party members by 10% every turn. That's right, every single turn.
Perna is definitely one to keep on your defense team.
2. Lapis: Water Magic Knight
I can't exactly remember when, but I got Lapis early on in the game. She is very good early game because of her leader skill which increases the attack power of her allies by 25%.
She made the list because she is a wonderful creature for a variety of reasons. Number one, all of her attacks hit multiple targets. Not only that, but her Magic Shot has a high chance of lowering the targets defense for two turns. To continue, her Retrieve Magic heals her according to however much damage she dealt, which is pretty much spell vamp.
I didn't research what runes to put on her because I was a newbie and kind of wanted to just follow my own instinct on things, so I gave her two energy runes for 15% HP and four fatal runes for 35% attack. However, I really want to exchange the fatal runes for four vampire runes that will give her life drain 35%. I feel like that would go good with her life steal from Retrieve Magic, but I'm not sure yet. I'll have to try it out.
She is the best magic knight to get and comes up as one of the most used monsters on all of the lists, falling in first place the majority of the time, coming in second for the rest.
3. Lucien: Light Elven Ranger
The only elven rangers worth noting are the fire and light rangers. I have not had any experience with the fire ranger, but the light ranger has been in my primary party since I acquired him.
Like other simple attack rune combinations, I had and still have him equipped with four fatal runes for the +35% attack. Pairing nicely with that, I also have him equipped with two blade runes for that +12% critical rate. That may not seem like much, but the actual critical rate equates to 42% because of the bonuses that have come with his runes through upgrading them.
Something to note about Lucien is that he's a glass canon, at least with my rune combination. He is very squishy, even though he does massive amounts of damage. I haven't done anything to address this yet other than keep my light fairy in the party with him to shield and heal him.
His attacks aren't really anything special other than his Ankle Shot and Steady Shot. Ankle Shot has a 30% chance to stun your enemy, which can be really useful against beefy foes. Steady Shot will deal an extra 50% damage if the target is stunned, frozen, or asleep. This being said, he can be deadly if paired with another monster that inflicts any of the status effects listed above.
4. Taor: Water Chimera
I am absolutely stunned by the mechanics of the water chimeras. While I haven't had the honor of summoning one myself, there are a few who have them on my friends list.
So far, I have used Taor in the dungeons for get further along in them and in the daily rifts that open up. From what I've witnessed, they're not one to underestimate. Not only does Taor have an attack that hits all of the enemies, Crush, but Squall, which does more damage according to the attack speed of your Taor. If you land a critical hit using Squall, it'll raise his attack speed for two turns.
After asking around and doing a bit of my own research, I've found that most people equip their Taor with swift runes to raise his speed by 25% and blade runes to raise his critical chance by 12%. Another less popular combination I found was four violent runes for a 22% chance of an extra turn and the two blades runes for the extra critical chance.
5. Ran: Dark Rakshasa
When reading the user rating for Ran, the dark rakshasa, you'll find that Ran is apparently fantastic when it comes to Necropolis and raids, but you don't really find any other helpful information.
Ran, I feel is underappreciated. you see many other monsters like Perna and Lushen getting talked about constantly in chat, but nothing much about the rakshasas or even Ran herself. This is where that changes.
Ran is excellent for clearing the various dungeons. Her Devil's Whip hits four times and has a 75% chance to decrease the opponents attack bar by 30% and if it fully depletes the targets attack bar, the enemy is stunned for a turn. Fast Swing, her next attack, scales on her speed. It does more damage the higher his speed stat is, but it'll also inflict continuous damage if you inflict a critical hit. Her basic attack has a 50% chance to decrease the enemies attack speed.
Again, I haven't really found much about runes for her either so I had to ask those in chat. The conclusion I came to is that vampire runes for life drain +35% and revenge runes for 15% chance to counter attack are what most used for sustain.