Beginner Team Building [UPDATED 8/23; formation advice needed!]

UPDATED 8/23

Hello everyone, I am a relatively new player (10 days), and I have a few questions about team building.

TLDR Version at bottom of post.

I am level 31, red guild
My current formation is (all level 20)

Name | Stat Total | Skill
Furnace Dragon+ | 5659 | Preemptive Strike
Hellfire Talos+ | 4522 | Critical Up
Child of Pit+ | 4318 | Agility Up
Cruel Black Wings+ | 3785 | Decrease Defense
Dark Elf Berserker + | 4773 | Preemptive Strike

I have a Ladon+ who I am in the process of leveling up, so I can replace Dark Elf Berserker +

My rationalization is that pre-emptive strike is the least valuable skill out of my team's skill pool (*if this is incorrect from a veteran perspective, PLEASE tell me what the skill prioritization is). I also think decrease defense, and agility up are both valuable skills (*), which make Cruel Wings+ and Pit+ both unchangeable members of my roster. Next; Furnace+ and Talos+ are both high skill-total mons with high damage output, and in battles I notice it's the two of them that do the bulk of the killing. So I don't want to move them.

Thus; my initial assesment is that Dark Elf Berserker+ should be replaced with Ladon+. Is this a good move?

Otherwise; what are some general intermediate team building tips/suggestions for my current setup? I know higher level players go for race(demon, wyrm), flying, etc... combos, so far I've managed to gear mine towards rarity, type, level. I am interested in 'cheaper' solutions; I'm sure a team of all AAs or As like balrog would be great, but I don't really have anything valuable or rare mon-wise, and I don't have many eps (I've got one); nor do I buy or plan on buying them. That being said; from a veteran perspective; who are the weakest mons on my team? What are some decently priced mons I should try to get to replace them?

TLDR: What are some mid-long term changes I should make to my team? Who are the weakest mons on my team, what are effective affordable red As?

Well, I'm just gonna go out on a limb and say that the easiest thing to do RIGHT NOW is stick with the Sin monsters you have. Not sure what your guild is (assuming Sin!) so I'm gonna sneak away from that. They're not a BAD team and the combo bonus isn't bad. If they're stuck at low level and you really need the fodder, you might try trading off the GHW+ for 5 c/c+. Yes its a loss, but its just taking up space anyhow.

Mid to long term goals: suck it up after the drops of darkness event is over and farm the beginning missions for squishables. Work on trades and pray for good luck from ally summons. As you get a nice pool of things that you like, work from there. For instance: I have a team that's mixed Impulse all at the same level (Beelebub, Blood Blob, Black Gear Wraith, Scrap meat Zombie, Hellfire Talos and Scorn BW, all A+). I have alternates that give me a brute or winged combo, but they're works in progress and you can't complain about the rarity/level/impulse combos together. Just be patient (since I'm not sure what level you are) but trust me, the game slows you down anyhow in the later missions. Stupid 2% completion for 14 energy >

I am in sin guild. I actually am planning on farming mission 4.4 (no collectable drop, highest gold rewarding 1 energy mission; only monster drops) as soon as the drops even is over. The current missions I'm on are 6 energy per turn, seems kinda strange since missions prior to it worked up to 9 energy per turn, then dropped back to 6, oh well.

I'm level 29 at the moment.

Still wondering about advice about which monsters on my team should be first to be replaced, and what some low-cost red monster options are.

Also anybody know how much ladon and fafnir are worth?

.bump