There's gonna be significant changes to talents over the upcoming updates, including 6th and 7th tier talents.
This is great news! All the best on working for the updates!
I don't know what this could contribute to the gameplay, honestly. You either got detection or you don't. I can see a stealth mechanic as a part of a bossfight, but otherwise, I don't see much use for it.
I think it will be a great addition to the game, if a boss goes invisible for a few seconds and breaks invis with extra damage when attacking a player.
Here are some of my personal suggestions for tier 6 talents for each class if you don't mind.
Bishop
Tenets of Souls tier 6
Mend now heals faster (faster ticks of healing) and more (spell power x 9) over 7 seconds
Tenets of Wrath tier 6
Your healing spells have a small chance to "crit" on heal(basically you heal more)
Tenets of Guidence tier 6
While casting Resurrection during battle, you gain 40 armor and all resistance.
Monk
Martial Arts tier 6
Increases elemental damage by 10% and elemental damage by other units to that target by 4% .Stacks up to 5 times. Final hit deals 5 Elemental damage and consuming the debuff. (Reaching the final hit much faster)
Peace of Mind tier 6
Steel Body now gain (0.10 x Level) resistance as well
Endurance tier 6
Ability to evade magic damage completely, suggesting 5%-10%.
Sorcerer
Conjuration tier 6
Meteor Strike tier 5 talent now seeks the target/targets over a wide area.
Invocation tier 6
Whenever you cast a spell, you gain 5% spell haste/ 5 spell power. Stacks 4 times, buff lasting 5 seconds.
Enchanting tier 6
Summons 2 water elements
Necromancer
Black Magic tier 6
Increasing the max number of skeletons summoned.
Elemental Magic tier 6
Detonating Bones now deals additional spell power x 3 burning damage over 5 seconds and causes a minor knock back on mobs. (Except bosses)
Blood Magic tier 6
Reduces the mana cost of all spells by 2, spells now uses hit-points to cast instead of mana. If the spell deals a critical strike, you gain for 5% of the damage dealt back in health.
Hunter
Archery tier 6
You have a 5% chance to hit extra 1.5 x physical damage on normal attacks and mini stuns the target. Mini stun does not work on bosses.
Pathfinding tier 6
Units that you attack with be marked with a de-buff, you and all allies around you deal 8% more damage to the target, your attacks also has reduced threat against the target.
Animal Bonds tier 6
Servent of Nature now attacks more rapidly and generates more threat as you take damage.
Druid
Preservation tier 6
Continue to cast 'Remedy' while moving, attacking however cancels it.
Avenger tier 6
When one of your summon dies, you can Resurrect it immediately. (Summon button)
Growth tier 6
Nymph now heals two allies at the same time.
Assassin
Dueling tier 6
Every 8th hit reduces the armor of the target by 1. Capped at 0.5 x level.
Ambush tier 6
Every 10th attack creates a shadow clone that attacks the target once from behind dealing 1 x attack power.
Perfidious Tricks tier 6
Dazing Trap can now be used in combat, if used on bosses, it reduces the attack speed of affected unit by 25% for 2 seconds. (ON BOSS ONLY)
Bard
Lorekeeper tier 6
You can use steal twice on the same target, reduces 'steal' cool down by 30 seconds.
Minstrel tier 6
Songs last even after bard lost visibility range of the user / Bard dies.
Bladedancer tier 6
Units affected by songs gains 10 all resistence and 5% evasion
Crusader
Leadership tier 6
'Crucify' now heals for the damage dealt to all allies except the caster(Crusader) in the area.
Tactics tier 6
'Hateful Strike', 'sheild bash' and 'Revenge' requires 5 mana to cast, but deals additional 25% holy damage.
Virtue tier 6
Removes strength penalty on 'Celestial Zeal'.
Berserker
Valor tier 6
When reaching 25% hit point, Berserker enters heroic mode, spells cause no mana and have reduced 30% cooldown. Buff last 10 seconds even after Berserker is being healed over 25% hit points.
Fury tier 6
'Lightning Blade' and 'Heaven's Edge' has decreased threat generation and 15% more damage.
Vigor tier 6
Berserker can hold 2 handed weapons and equipping a shield
OR
1 handed weapons now has the same splash ability as 2 handed