I think a less drastic rebuild could be equally if not more effective, but that Archmage should be a generalist, rather than a specialist caster (that was a separate basic caster option in 3.5e)
In fact, I think the biggest mistake made in the original AM tree is trying to make it a specialist caster without really supporting school specialization.
I'll take a shot at reimagining Archmage as a generalist caster while allowing it to work in DDO where everything is balanced against maximal overspecialization:
Core 1: Each core ability in this tree grants +7 universal spellpower; Each point spent in this tree grants 2 SP; Select a spell school, gain a permanent effect based of the chosen school:
- Aburation: Gain permanent Nightshield
- Conjuration: Gain the Augment Summoning Feat
- Enchantment: Gain +1 Spell Penetration
- Evocation: Gain +5 Spellcraft
- Illusion: Gain Invisibility SLA
- Necromancy: You are immune to Fear effects
- Transmutation: All weapons and armor you equip gain +1 enhancement bonus; weapons also gain +3 Implement bonus to spellpower.
Core 2: Reduce the cost of all Metamagic feats by 1. If you posses Augment summoning, +1 to all stats of summoned creatures; If you possess Mental Toughness, gain 1% crit chance for all spells; Select a school other than that chosen for Core 1, gain an effect or SLA:
- Aburation: Nightshield grants +10 MRR and MRR cap
- Conjuration: Web SLA
- Enchantment: Gain Resistible Dance SLA
- Evocation: Gain +5 Spellcraft
- Illusion: You are always under the effect of the Blur spell
- Necromancy: Gain Scare SLA
- Transmutation: All weapons and armor you equip gain +1 enhancement bonus; weapons also gain +3 Implement bonus to spellpower.
Core 3: Gain +1 all DCs, and an additional +5 Universal Spell Power; If you possess Augment summoning, +1 to all stats and +25% fortification for summoned creatures; If you possess Mental Toughness, gain 1% crit chance for all spells and +50SP; Select a school and gain the associated SLA:
- Aburation: Gain Stoneskin SLA; your stoneskin also grants 10 PRR
- Conjuration: Acid Rain SLA
- Enchantment: Gain Hold Person SLA
- Evocation: Gain Chain Missiles SLA
- Illusion: Gain Displacement SLA
- Necromancy: Gain Burning Blood SLA
- Transmutation: Gain Haste SLA
Core 4: Gain +1 all DCs; Gain +1% crit chance for all spells; Gain +1 to DCs to all spell schools selected in Core 1-3; If you possess Augment Summoning, +2 all stats for all summoned creatures; Select an SLA or effect from the list:
- Aburation: Gain Protection from Elements SLA; This SLA has no Max Caster Level
- Conjuration: Summon Moster V SLA; +2 all stats for all conjured creatures
- Enchantment: Gain Hold Monster SLA; +1 Spell Penetration
- Evocation: Gain Cyclonic Blast SLA; +10 Force Spell Power
- Illusion: Gain Phantasmal Killer SLA; Phantasmal Killer deals 2d3+6/caster level on a successful fort save
- Necromancy: Gain Enervation SLA; You are immune to level drain
- Transmutation: Flesh to Stone SLA; Your weapons gain an additional +1 enhancement bonus and +3 implement bonus to spell power
Core 5: +1 all DCs; Reduce the cost of all metamagic feats by an additional 1. If you possess Improved Mental Toughness, gain 1% crit chance to all spells and 100SP; if you possess Mobile Spellcasting, reduce the cost of Quicken Spell by 2; Greater Spell Focus feats grant an additional +1 DC; Select a school effect from the list:
- Aburation: Your abjuration spells also grant temp HP equal to your Int modifier to you, and all party members in the area of effect.
- Conjuration: Your offensive conjuration spells have a 2% chance to Trap the Soul; Your summons are immune to banishment and death effects
- Enchantment: Your Enchantments gain the Widen Spell metamagic, doubling their area of effect
- Evocation: Reduce the Cooldown of Evocation spells by 10%
- Illusion: While Displaced, your spells generate 50% less threat; while invisible, gain 5% spell crit chance
- Necromancy: Your offensive necromancy spells heal you for 1 damage per target per caster level; if you are in an undead shroud, you are healed for 1 negative damage per target per caster level, and 50% of overhealing is added as temporary HP for 1 minute (stacks with other sources of temp HP but not itself)
- Transmutation: Gain 20 PRR, 10 MRR and DR 10/Crystal
Core 6: +4 Int; +5 Spellcraft; reduce the cost of metamagic feats by an additional 1; Apply the Eschew Components feat to all your spells. Arcane Scrolls you use are cast at your caster level, and are heightened and maximized if you possess those feats.
Tier 1:
- Subtle Spell Casting: Your damaging spells generate 10%/20%/30% less hate.(3 Tiers, 1AP)
- Energy Of The Scholar: Increase your maximum Spell Points by an additional 30/60/100(3 tiers, 1AP)
- Mastery of Spellcraft: Increase your Spellcraft Skill by 2/4/6 points; 25%/+50%/+75% effectiveness from your wands, scrolls, and other items that cast spells, and +1/+3/+6 to the save DC of your offensive wands. This will block Wand and Scroll Mastery in other enhancement trees.(3 tiers, 1 AP)
- Traditionalist Caster: Gain 3/6/10 Universal Spellpower when wielding an Orb or 5/10/15 when wielding a staff (3 tiers, 1AP)
- Arcane Critical: Gain 1% crit rate for acid/cold/electric/fire/untyped and 2% for force spells (2AP)
Tier 2:
- Efficient Metamagic: Choose one meta magic to reduce the increased spell cost by a certain amount based on the chosen Metamagic. (Can Choose from all available Metamagics except epics, 3 Tiers, 2 AP)
- Spell Penetration: +1 Spell Penetration. (2 tiers, 1 AP)
- Arcane Bolt: Gain Arcane Bolt as an SLA. 6/4/2 SP 15/10/5 sec CD (3 tiers, 1 AP)
- Arcane Boost: Gain 10/20/30 Universal Spellpower for 20 seconds (3 tiers, 1AP)
- Arcane Critical I: Gain 1% crit rate for acid/cold/electric/fire/untyped and 2% for force spells (2AP)
Tier 3:
- Intelligence: +1 Intelligence (1 tier, 2AP)
- Arcane Surge: When Arcane Boost is activated, gain 15/30/50 temp SP for 20 seconds
- Arcane Vulnerability: Damaging spells have a 1% per wizard level chance to inflict a stack of Vulnerability (2AP)
- Arcane Power I: Increase Universal spellpower by 3/6/10 points (3 tiers, 1AP)
- Arcane Critical II: Gain 1% crit rate for acid/cold/electric/fire/untyped and 2% for force spells (2AP)
Tier 4:
- Intelligence: +1 Intelligence (1 tier, 2AP)
- Arcane Unravelling: Gain 3/6/10 MRR and 10/20/30 MRR cap (3 tiers, 2AP)
- Arcane Utility: Casting a non-damaging spell has a 33/66/100% chance to grant you 10 temporary SP (3 tiers, 1AP)
- Arcane Power II: Increase Universal spell power by 5/10/10 points; at tier 3 gain +1 all DCs. (3 tiers, 2AP)
- Arcane Critical III: Gain 1% crit rate for acid/cold/electric/fire/untyped and 2% for force spells (2AP)
Tier 5:
- Spell Like Ability: Arcane Blast. (Activation Cost: 12/8/6 Spell Points. Cooldown: 18/12/6 seconds.) (3tiers, 1AP)
Raw arcane energy assails your target, dealing 1 to 6 hit points of force damage per caster level to all within its radius, and leaves the survivors dazed, the force of the blast may knock your opponents off their feet. A successful Reflex save reduces the damage by half; a successful Fort save negates the knockdown; a successful will save negates the daze effect - Will of the Archmagus: You may use your Int modifier instead of wisdom for Will saves (1 tier, 2AP)
- Flash of Insight: shorten all spell and SLA cooldowns by 60 Seconds; Cooldown: 600 seconds (1tier, 2AP)
- Arcane Augmentation: Gain 1/2 Caster Level/MCL to all spells (2 tier, 2AP)