All of the above

slot 1 main stat is fixed to ATK (flat value)
slot 3 main stat is fixed to DEF (flat value)
slot 5 main stat is fixed to HP (flat value)

slot 2 main stat can be ATK/DEF/HP (both flat and %), or special stat SPD
slot 4 main stat can be ATK/DEF/HP (both flat and %), or special stat crit rate% / crit dmg%
slot 6 main stat can be ATK/DEF/HP (both flat and %), or special stat accuracy% / resistance%

ATK/DEF/HP% scale much better when you are high level compared to the flat values (example, a 6* ATK% rune at +15 is 63% of your base stat. with all 3 slots 2/4/6 set to ATK%, you can get 189% boost to attack stat!). this is how you can see attacker with 800+2000 attack or tank with 12000+30000 HP

Also, the special stat is needed to build specialized skillset, such as Bernard that always has the first turn (with swift runes 25% speed and 6* slot2 SPD rune adding 42 speed and speed substat on every runes), 100% resistance Rina, which will almost never get stun, etc.

at this moment i got few mob

Fresh
- Beast hunter - Wind
- Living Armor - Fire
- Bounty Hunter - Water
- Bearman - Fire

Lv 3 Max
- Garuda - wind [can be a good stun monster]
- Harpy - Light [fastest speed booster in game]
- Hellhound - Fire [good damage and good buff]
- Golem - Fire
- Bounty Hunter - water [speed booster. but i think light harpy is better]

Lv4.
- Fairy - Water [decent monster for early/mid game]

i see wrongly. light garuda and wind harpy

this look damn nice to which to focus at first. as current i only focus upgrade fairy which is lv 5 already but yet i unable to win those boss

but what is the rainbowmoon for? i got 5 of it don't know what to do with it

mean that if i got lv 4 rainbowmon it will make my fairy lv 4 to lv 5 directly? by using one?

Hey guys, have been playing for about 2 months now, still kinda lost on what I should focus on. 

Any advises can you give to me if I wanna focus on Giants? Thanks!

The mobs that I have:

for dungeon, bella/ahman to 6*, delphoi to 5*

how ur guys doing??? 

after 1 year dint touch her. 
today play back 
boring punya pasal 

seen like this games got alot new mobs and alot new features 

+1000 social point summon
+200 unknown scroll
+7 mystical scroll

and so many rubish mobs, dono how to kao tim??? 

why LYNN guide so less member liao de???
15/30 

and what is guide battle?

what LINE group, can i join? hehe.. not dare to enter any guild at the moment, feeling nub dont have 6* monster yet 
Edit: after playing back for 10 days+, finally got my first nat 5* wind chimera