These are my current, although broad and generalised, thoughts about the relative value of the different types of Relics, all IMO and FWIW, which may assist others in deciding which to prioritise.
First, some initial comments.
It is not universally the case that the higher the rarity the better the Relic. As a generalisation yes. But there are some Diamond Relics that are only ok, and some Bronze Relics that shine.
The circumstances under which a Relic triggers greatly influences its viability. Relics that trigger at start of battle are plainly more valuable than those triggering at end of turn if life is under a %, for example. Generally. Healing and Energy Gain are exceptions, natch.
The trigger conditions could justifiably form the basis of a separate analysis, examining builds created to leverage triggers (such as possession builds seeking to maximise the damage possessed victims do to their teammates) - but ultimately these comments focus on the Perks instead.
Don't. Identify those you wish to prioritise, and sacrifice everything else to the Forge. That Oniric Armor? Burn it for the greater good.
SP's decision to allow removal for gold rather than gems means that you do not need a huge inventory. Dont obsess about it: be ruthless about sacrificing excess duplicates to the forge. That fourth Charging Banner? You know you can only field 3 monsters at a time, right?
So. Perks Categories.
Armor cannot be stripped, and lasts until depleted (unlike stat boost Relics which last a turn or two). Armor allows fast teams to become tanky, and tanky teams to become juggernauts. Armor keeps your monsters alive. Not flash or cunning, just plain effective.
This is IMO the best category of Perk.
Armor Relics also include three with the prized trigger at start of battle: the Bronze Protection Amulet, and the Diamond - Atum's Armour (wearer) and Tenacity Shield (whole team), making those Relics among the best.
However, the Gold Relic Heavy Duty Armor is arguably better than the Diamond Atum's Armour. Since it activates twice (on hit), it actually provides greater protection in total. The trade off is that an OHK on a monster wearing Heavy Duty Armor prevents activation at all.
Upshot: on a high life monster not at risk of viable OHK, the Gold relic is better, but where OHK is a risk, the Diamond relic is preferable.
There is a good Bronze Relic in this category: the Protection Amulet. At max level, it gives 10,480 points of Armor to a random ally - at the start of the battle. Yes, random ally but still enough Armor to frustrate an attack plan. More so in fact because it is random - preventing certain attack planning.
The Gold Ice-Breaking Greatsword deserves a mention. At max level, it gives its wearer 30,600 armor and physical protection on hitting if its target after hitting is frozen or stunned. Great for a denier like Cavenfish. Triggers twice.
Healing Relics can be very effective. They are at their most effective in dealing with lower damage extra turn attackers, where they can heal more damage than is taken. But, frankly, this is more annoyance value than anything else since an extra turn monster can usually attack more times than healing relics can trigger.
Ultimately, Armor Relics are more effective. They have no maximum (unlike healing, which can't exceed max life), and they essentially add 'life' without first needing to be damaged. Also, negative healing effects do interact with this Perk, so that your healing Relic can kill you.
Compare two Gold Relics: Heavy Duty Armor and Healing Mask. Both trigger twice, when hit - the Armor regardless, the Mask if wearer has less then 50% life. At max level, the Armor gives 30,600 points of Armor (self). The Mask heals 39,080 (self). But to gain the full benefit of the heal, the monster must have taken more damage than that, while the Armor is unconstrained. I favour the certainty of Armor.
One of the best Bronze Relics are in this category: the Healing Amulet. At max level it heals when the turn starts, if the wearer's Life is below 50%, by 21,565 points. 2 uses.
- Increase Max Life
This is a mixed bag. They tend to last a turn or two at most. In that period, damage comes off the increased life so in a sense it is like armor - but temporary so inferior.
Some trigger on hit (Comeback Essence) and some at start of turn (Vitality Banner) and some even at start of battle, so the triggers are relatively good.
But although useful, this Perk is not as valuable as Armor for several reasons. First, the values are comparable to armor. So no number advantage. Second, it works proportionately. It does not increase life, but max life. If you are at 50% life, and your max life increases by 10,000 (eg), your life total increases by 5,000. For a turn or two. Third, DoT is calculated from max life. So if your monster has taken damage and max life increases, it will take more DoT both in actual value and as a proportion of actual current life.
There is an excellent Bronze Relic in this category: Vitality Essence. Once the battle begins, the wearer's Maximum Life is increased by (1,250 to 15,260) points. 2 uses.
- Decrease Max Life
Currently, only the Silver Pestilence Trap has this Perk.
Now these are interesting, because they synergise with Relics that trigger based on % life. Like the Jakugan Sword (which triggers if, after hitting, the target has less than 50% life).
The traps reduce the amount of damage an attacker needs to do to trigger the swords, allowing a potentially effective full speed, up front, hitter.
This is my current pvp defence project, where I have found the optimal balance to be 5 Traps and 1 Sword. 5 maxed Traps decrease all enemies' max life by 29,050, making it far easier for an all speed hitter to trigger the Sword for a bonus 12,325 damage. Crissandre, for example, using her 45pt Bleed AoE, triggers her Sword if any target hit had starting life under 50,278 (for total AoE 'damage' of 51,989) on opening.
- Increase Power.
It must be remembered that the Power stat plays a relatively small role in the damage calculation, and that fact undermines the effectiveness of this Perk.
Balthasar's Mask serves a useful example. It triggers at turn start. Lasts 1 round. Triggers twice.
Level 1 - Power + 720, which translates to an extra 39 points of damage per skill attack point. Example: a 35pt AOE will do an extra 39 x 35 = 1365 damage. A 70pt single attack will do an extra 39 x 70 = 2730 damage.
Level 40 - Power + 2520, which translates to an extra 136 points of damage per skill attack point. Example: a 35pt AOE will do an extra 136 x 35 = 4760 damage. A 70pt single attack will do an extra 136 x 70 = 9520 damage.
Not peanuts. But hardly earth shattering. Not at all relatively desirable.
NOTE the power add takes place after strength rune increase is added. So it is not boosted by strength runes.
- Energy Drain
Well, this Perk has arguably had the greatest impact on the tactical landscape. If it were not so readily countered by Energy Gain Relics, this Perk would be broken.
There are many Relics in this category, with both attacking and defending triggers. Monsters like Dr Viktor with two Oblation Staves add full energy drain to their AoE skills (Burn, Blind, and full energy drain is nice, as is AoE Stun and drain). Monsters with Trap slots force extra turn monsters to watch energy management and targetting since Oblation Traps drain the entire attacking team. Mixing Exhausting Masks (trigger on hit) with Oblation Traps (trigger on hit if under 50% life) provide wide spectrum energy drain that can foil extra turn attackers even if they are running Energy Gain Relics.
Apart from anything else, these Relics force the attacker to use up Relic slots to counteract them.
- Energy Gain
These have finally put Thetys in her place, although she remains relevant due to Elite Sea Troops.
Apart from anything else, these Relics are essential due to the prevalence of Energy Drain Relics.
Charging Banner is excellent, not least because they can be carried by Zyla and Thetys herself (negating the down side of Stamina Devourers). It doesn't even have to be highly ranked, because it reaches the 40 energy threshold easily and triggers 3 times.
The Diamond Cane of the Atlantis gives good energy return, to all allies, and triggers when any ally has under 50% energy. But only twice. This makes it less useful than the Charging Banner, because the Energy Drain landscape is fully capable of taking all your energy in one go, so the number of times the Relic triggers is more important than the amount of energy it gives, especially for extra turners.
Don't overlook the Bronze Energizing Amulet. At max, when the turn starts, if the wearer's Stamina is below 50%, it gains 45 points of Stamina. 2 uses.
Currently, only the infamous Uriel Essence has this Perk. And yes, nice, but not as awesome as might be expected.
Firstly, by now most everyone knows to kill a monster wearing one, last. Resurrecting alone, with comparatively low life, and lacking team speed from its dead allies it goes down the turn order where it is an annoyance rather than a problem.
It has some advantageous aspects to be sure. A team all carrying Uriel's Essence is troublesome (think Llum, Valgar, Cloud, Jasastur). A team calibrated to have a low life (C UC R) monster carrying Uriel's Essence and ready to draw fire and die on opening allows bypassing a fast opener through turn order reset on resurrection (resets turn order then skips the first), letting a canny attacker slip a slower, strength augmented, attack team past the first line of defence.
In addition, this Perk can be made to synergise with other Relics that trigger when the wearer has life under a threshold since it will resurrect under the threshold. So, eg, Osur's Amulet triggers when the wearer has under 75% life. Valgar wearing both will resurrect and immediately activate the Amulet.
There could be excellent synergy with Relics which trigger "when revived" - but, at present at least, those Relics are underwhelming.
There are a few of these. Revenge helmets, Taiga Trap, swords that inflict elemental damage when target conditions are met or on death, Jakugan Sword, and the Cold Staff. The helmets, staff, and lesser swords dont do enough damage to make an impact.
The Taiga Trap has great possibilities because it triggers 3 times and does respectable (light) damage (at max, 20,545 damage). However, it triggers when the wearer has under 50% life, and unless the wearer is a tank, the Relic is unlikely to get much opportunity to trigger 3 times. Neverthless, a team carrying a bunch of these could be very effective indeed.
The Jakugan Sword is excellent, not least because Zyla can carry one, extending her damage output and kill range significantly. It only triggers twice, and only if the target has under 50% life after being hit (see Pestilence Traps comments above), for 12,350 damage to all enemies at max level. For Zyla, that is 12,350 x 2 triggers x 3 enemies - 74,100 additional damage output. My Zyla no longer uses stamina or strength runes, just Sword and Banner. Note that this is Physical Damage (ie pierces Looped Damage).
An additional bonus: if the wielder is possessed and hits an ally triggering the Sword, the Perk still damages the enemy.
A downside: lethal damage from Relics is ignored when the app checks whether a Healing Relic activates, so the Relic damage does not prevent the victim healing from dead.
- Speed and Slow
It is hard to assess these, while the turn order recalculation mechanic is so flawed. At present, both of these categories are a lottery - they could mean you don't get another turn for a bit, whether or not they are supposed to benefit you. And that flaw is exacerbated because these perks last a turn or two and then values revert, putting you at the mercy of the broken turn recalculation twice.
The Machiavellian among us will see that these are potentially effective on defence, subjecting the attacker to the whims of the turn order algorithm. Whether that is appropriate use of these Relics (exploiting a known glitch) is a matter for debate.