Credit goes to Ryan914 for this guide.

When combat is initiated, the character names of your active party will be at the bottom. The Time Gauge will be above the character names and enemies above the time Gauge. Above the Time Gauge are the FE Slots. The game uses a first person battle screen like Dragon Quest and other older RPGMaker games.

To select skills, press left or right when it's a character's turn. To use the variations of the skill, press down and up.

Normal Attack/Hard Attack
Ability
Defense/Hard Defense
Item
Pass (Pressing Up and Down will let the player pass a characters turn by a certain length of time based on the ATKWT, at times this may be useful when planning in battle)
Enemy Data: See the enemies stats

*Note: ATKWT is known as Attack Waiting Time

Pressing shift will give a second options list: Which has the following:

ATKWT Check: See the ATKWT of all units
Escape: Attempt to escape battle
Battle Reference: Will list the battle interface and other information

Time Gauge:

Each unit gets a turn when the unit itself reaches the left hand of the gauge. Also, when a unit selects an action, a red icon will appear on the gauge indicating tentatively where the unit will end up in the gauge if the unit was to perform the action.

The enemies point on the time gauge is on the upper half and the numbers represent their locations from left to right on the screen. (Unit one of enemies will always be on the left side). Your units point on the time gauge is on the lower half and numbers represent their location in the bottom half of the screen. (Top most unit is considered unit 1)

A lower ATKWT stat means a higher priority to act in battle. Each skill and spell will move the user to a specific point indicated in red on the Time Gauge.

Field Elements: (FE)
Field Elements are a key battle mechanic in Seraphic Blue, most if not all higher level abilities require that an FE be applied in order to be used. FEs can be applied as a result of using lower level elemental magic and abilities.

Example: Use Watery to be able to access Life Rain

On the bottom right part of the battle screen, above the time gauge there are 5 spheres. When battle is initiated they will mostly be empty.

We will call them FE Slots 1-5 for reference. The far left being 1 and the far right being 5. The first 3 can be cancelled out by an opposing FE. The last 2 can only be cancelled through skills or magic that can dispel it. Example: If the FE in slot 1 is fire, using water will make it empty, using water again will make the FE Slot water based.

FE Slot 1: Fire/Water (Red/Blue)
FE Slot 2: Wind/Earth (Brown/Yellow)
FE Slot 3: Light/Dark (Yellow/Black)
FE Slot 4: Sky (White)
FE Slot 5: Break (Pink)

Buffs: (These are the last 4 slots in the HP/MP menu of the party in battle)

Protect:
Boosts DEF.

Clever:
Boosts MEN and MDF.

Quick:
Boosts AGI.

Force:
Boosts ATK.

Ailments: (These are the 11 slots in the HP/MP menu of the party in battle)

Death:
A Dead party member, ie. HP = 0, cannot perform any actions in battle unless revived.

Stone:
A stoned party member cannot perform any actions in battle unless Stone is removed

* Game is over if all allies are Dead and/or Stoned

Poison:
A poisoned party member suffers damage equal to 20% of his/her max HP per turn

Disease:
A diseased party member suffers damage equal to that of Poison status in addition to weakened ATK and DEF, and all positive status denied (All status buffs negated and member afflicted can't gain buffs)

Paralyze:
A paralyzed party member cannot perform any actions in battle unless Paralyze is removed.

Slow:
A party member inflicted with Slow travels slower in the Time Gauge. (Increased ATKWT)

Blind:
A blind party member has HIT weakened in addition to all physical abilities disabled.

Forget:
A Party member inflicted with Forget has MEN & MDF weakened and all mental abilities are disabled. Also suffers 5% damage of max TP per turn.

Confuse:
A confused party member has no control over his/her actions and randomly attacks an ally per turn. A physical attack on him/her removes this status.

Melancholy:
A party member inflicted with Melancholy has ATK, DEF, MEN, AGI & AVD weakened, and all positive statuses denied. (All status buffs negated and member afflicted can't gain buffs)

Most of this is in the battle reference section. I just typed it down to save people the trouble of figuring something cryptic out.

Both buffs and ailments will be given specific letters and colors. Characters can get multiple ailments at once. (Example: Confuse and Disease could be applied due to the enemy you are facing having abilities that can inflict them) However the same goes for buffs. The player can apply buffs for each ability. (The buffs and ailments do not have a cumulative effect aside from Poison and Disease both being applied at once which means 40% max HP damage per turn is lost. This means that once applied, the ailments/buffs do not stack, they will not increase after application.)

Note: You can multi target enemies with offensive magic by pressing up after selecting the spells. The same goes for healing as well. You can heal multiple allies by pressing left/right after choosing healing magic.

You can alter the effect of healing items using the Up Substances. It will cost 2 Healing items to double the effect (D), and 4 to cover the whole party (A). It gets rather expensive to upgrade them though, but well worth it if in a pinch or going to boss.
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Another friendly reminder. Clanas and other certain items that can restore TP can be dropped by enemies, however the rates vary depending on the point in the story, however you should also be able to buy them around Ep 36:

Clanas are quite expensive, usually costs around 20K for just a regular one (40 TP). The Full Clana costs a whopping 1 Million Dear, also all Clanas sell for only 10 Dear.

Clana:

Ep 1: 3.7%, Ep 13: 22%, Ep 23: 0.5%, Ep 31: 0.5%, Ep 36: 0%

Great Clana:

Ep 1: 1%, Ep 13: 1.9%, Ep 23: 25%, Ep31: 1.7%, Ep 36: 1.2%

Ex Clana:

Ep 1: 0%, Ep 13: 0.5%, Ep 23: 1.2%, Ep31: 1.6%, Ep 36: 22%

Full Clana:

Ep 1: 0%, Ep 13: 0%, Ep 23: 0.2%, Ep31: 0.3%, Ep 36: 0.4%

God's Half Elixir:

Ep 1: 0.2%, Ep 13: 0.3%, Ep 23: 0.4%, Ep31: 0.5%, Ep 36: 0.6%

God's Elixir:

Ep 1: 0.1%, Ep 13: 0.1%, Ep 23: 0.2%, Ep31: 0.3%, Ep 36: 0.4%

Maria's Will:

Ep 1: 0%, Ep 13: 0%, Ep 23: 0%, Ep31: 0.1%, Ep 36: 0.2%