Last Update: April 2011
Optimizing Arcana
Reasons for high Arcana
The Sage of the Ages epic destiny utility power allows for some very
very beautiful things, assuming you get your arcana check high enough:
Trick of Knowledge (Utility 26)
Encounter * Arcane
Minor Action * Personal
Effect: Make an arcana check and gain a benefit based on your check result until the end of the encounter.
30 or lower: no effect
31-35: +5 to saving throws
36-40: +2 bonus to all defenses
41-45: +2 to arcane attack rolls
46-50: make saves at the beginning of your turn instead of end.
51-55: pick 2 of the below benefits
56-60: pick 3
61 or higher: pick 4
... in other words, with good optimization you will get +5 to saves, +2 to all defenses, +2 to attacks, and save at the start of your turn.
Other benefits of high Arcana
Sorcerous Vision (feat, AP): Use Arcana check for Insight and Perception checks (requires Sorcerer class or MC Sorcerer)
Suggestion (free mage utility power, HotfL): Use Arcana instead of Diplomacy
Arcane Mutterings (lvl2 encounter skill power, dragon 379): Use Arcana instead of Bluff, Intimidate or Diplomacy check
Fools
Gold (lvl2 ritual, AP): Create illusionary gold, worth x100 component
cost. DC to find out: your arcana check. 10 gp -> 1000gp :D
Seek Rumor (lvl2 ritual, FRPG): Substitute Streetwise with Arcana to find out everything there is to know...
Knock (lvl2 ritual, PHB): Arcana+5 instead of Thievery to open locks
Mythic
Senses feat (PH3, requires Minotaur) - use Perception checks in place
of initiative checks - combine with sorcerous vision -> arcana
for initiative
Cunning Artifice (Dragon 387, requires Artificer, Changeling) - use Arcana for Bluff in changeling racial power
Autohypnosis (heroic feat, Psionic Power): Use Arcana for Endurance Checks if not bloodied
Arcane Trickster (PP): Use Arcana for Athletics Checks
How to get it
items bonus:
iron of spite (head, phb) +6 item bonus
runic armor (armor, av2) +6 item bonus
ring of wizardry (ring, phb) +3 item bonus
mirror of secrets (Artifact, Open Grave) +2/+4/+6 item bonus (concordance dependent)
opal ring of remembrance (ring, AV): +4 item bonus
staff of psicraft(staff, phb3): +1/+2/+3 item bonus
feat bonus:
skill focus (phb) +3 feat bonus
highborn drow (Dragon 364, requires drow) +2 feat bonus
power of arcana (Divine Power, domain) +2 feat bonus
yuirwood feyfriend (Dragon 370) +1 feat bonus
bardic knowledge (phb2) +2 feat bonus
Drowning of Nhalloth (Dragon 391, requires Shadar Kai) +2 feat bonus
Power bonus:
Inspire Competence +2 power (Bard encounter or Wand of Aptitude daily power)
Good Omens (Cleric PP Divine Oracle daily util, phb): +5 power bonus
Fevered Certainty of Caiphon (warlock daily util, dragon 366): +5 power bonus
Elexir of Aptitude (consumable, AV): +1/+3/+5 to skill check, lasts 1 hour, requires healing surge
Symbol of Excellence (holy symbol, AV): +1-6 power bonus, requires daily item use
CD: Ancestral Guidance is a power bonus of +Wisdom for one check. Requires Spirits of the Past.
CD:
Divine Excellence is +2 power to you, and grants a +2 power on the same
skill to you and all allies until the end of your next turn.
Requires skill domain.
Good Races:
Eldarin (phb) +2 to int, +2 to arcana
Gnome (phb2) +2 to int, +2 to arcana
Deva (phb2): +2 to int, Memory of a Thousand Lifetimes -> reroll with +1d6 bonus (+1d8 with feat)
Shardmind (phb3): +2 to int, +2 to arcana
Changeling (eberron) + feat: becomer (dragon 386): +2 int, +2 to arcana
Backgrounds
+2 (generic, phb2)
High Imaskar (FRPG): reroll arcana check, keep second result
Netheril (FRPG) +1
The Great Dale (FRPG) +1
Untyped bonuses
Paragon of Learning (ED Sage of Ages feature, AP) +6 untyped
Arcane Underpinning (PP Academy Master feature, dragon 374) +2 untyped
Dabbler (PP Jack-of-all-Trades feature, MP2) +2 untyped
Unseen Aid (Sorcerer encounter util, PHB2) +2 untyped
Mage class (for free, at level 21) +3 untyped
Disciple of Lore (heroic feat, HotFL) +1 untyped to all trained skills
Talent Shard (Consumable, minor action, PHB3) +1 to +6 untyped
Resourceful Action (Halfling PP Halfling Scoundrel feature, PHB2) +5 untyped, requires AP
Fate of the Void (Star Pact Warlock pact boon, PHB) +1 untyped/ enemy killed
Morans Eye (P1 King of the Trollhaunt Warrens, wonderous item/implement, probably unique) +5 untyped for posession
Moonstone Sphere (E1 Deaths Reach, wonderous item/implement, probably unique) +2 untyped for posession
Head of Vyrellis (H3 Pyramid of Shadows, wonderous item/implement, probably unique) +2 untyped for posession
Tacticans Armor (Armor, AV): +1 untyped (maybe, check wording with DM)Familiar: Book imp +2 (Dragon 374)
Familiar: Crafter Homunculus +2 (Dragon 374)
Familiar: Rakshasa Claw +2 (Dragon 374, paragon) + free action item stow/retrieve (could allow to switch head slot items?)
Familiar: Skull +2 (Dragon 374)
Familiar: Greyspawn Shortfang +2 (paragon) (Dragon 374)
Familiar: Blazing Skull +2 (epic) (Dragon 374)
Familiar: Chaos Shard +2 (epic) (Dragon 374)
Familiar: Coure Attendant +2 (Dragon 290)
Relics of Creation (AV2, epic item set): +2 to +6 (depending on # of setitems)
Bonuses granted by Allies
Aid Another: +2 untyped per character helping BUT: requires standard action -> not practical
Clockwork
Precision (Bard daily util, AP): aid another adds +3 untyped per
character helping, but still requires standard action -> not
practical
Find Another Way (Bard PP Lifesinger feature, AP) : +2 untyped for allies within 5 squares
Speak with Spirits (Shaman Class Feature, phb2) + feat Spirit Speaker: +wis bonus to skill check
Crucial
Advice (Ranger Util 2, phb, encounter, immediate reaction): reroll
check, with +wis power bonus, but works only on allies (not oneself)
Fatesinger Bard: Majestic Word -> roll twice, use better result
Glittergold's Gambit (Channel Divinity feat, FRPG) -> reroll attack roll or skill check
Golden Mean (Lord of Fate ED daily utility power, AP): take 10 on any check
CD:
Sune's Touch is for an ally. One ally in Close Burst 1 gets +2
power to his next skill check until the end of his next turn.
Rerolls
Potion of Clarity (consumable, AV, costs healing surge): reroll with +1 to +6 bonus
Arcane Insight (Wizard Util 2, Dragon 366, encounter, free action): reroll arcana check, use better result
Keeper's Prescience (Sage of the Ages 24 ability): roll d20 each round, switch result with any roll during that round
Dark One's Own Luck (Warlock Daily Util 6, PHB): reroll an attack roll, skill check, ability check, or saving throw
Kensei
Control Action (Fighter PP Kensei feature, PHB): AP->reroll attack
roll, damage roll, skill check or ability check (no extra action)
CD: Divine Fate is Revenant-only, but not tied to a deity and gives a RtB on any skill check.
CD:
Imminent Luck is GOOD. If you spend a power to reroll, and the
reroll is lower, you can expend CD: ID not to expend the power.
Requires only the luck domain. Note that this works with RtB powers.
Bonus to specific Arcana Checks
Note:
These bonuses won't work with Trick of Knowledge. But they might still
be of interest to get a high arcana result in other circumstances...
Consult Mystic Sages (ritual, skill:religion): Get +10 to an arcana check (specific purposes given in a list)
Arcane Ritualist (feat, AP): Get a untyped +2 bonus for one specific ritual
Foreign Memories (feat, Dragon 389): +5 feat bonus, only related to aberrant creatures
Oghmas Recall (feat/channel divinity power, FRPG): Get a +10 power bonus for a knowledge check
CD:
Aureon's Instruction is RtB (reroll take better) with knowledge or
monster knowledge checks until the end of your next turn. Requires
Aureon.
CD: Sure Knowledge is RtB for a knowledge check. Candidate for an ally feat, as it's you or an ally.
Historical Revelation (enc. Skill Power): ally can reroll knowledge check
Let your Familiar also make the check: especially useful for knowledge checks (since they are free actions)
Current maximum:
15(lvl)+9(int)+6(item)+5(trained)+2(race)+2(background)+6(ED)+2(familiar)+2(PP)+3(feat)+6(items
of creation)+6(talent shard) = +64
Which would allow us to
always roll 65 for all 4 benefits. Or roll
Insight/Perception/Bluff/Intimidate/Diplomacy/Streetwise/Thievery/Endurance/Athletics
+65. And Initiative +65. And your fools gold will be more real than
normal gold 
. But more versality is always better, since you usually don't want to optimize arcana only, more ways to get there or even higher are welcome...
