Three builds, one for each acorn and each of them having a different playstyle.
Critical squirrel focus on the lifesteal and critical hit.
Tanky squirrel is a more hybrid build.
Stunning nut squirrel use all of his skills and stuns a lot of enemies.

Bristlebush Acorn
PASSIVE: Dart deals 35% increased damage and can Critically Strike. When Dart damages an enemy Ratatoskr gains 10% Physical Lifesteal and 10% Basic Attack damage for 6s.

Asi
PASSIVE - If you drop below 35% Health, you gain an additional 30% Physical Lifesteal for 5 seconds. Can only occur once every 15 seconds.

Rage
PASSIVE - Killing or getting an assist on an enemy god gives you 1 stack. Each stack provides 3% Critical Strike Chance. Stacks are permanent and stack up to 5 times.

Bloodforge
PASSIVE - Killing an enemy god forges a shield from their blood with Health equal to 200 + 10 per Player Level for 20s. While the Blood Shield is active you gain +10% movement speed.

Malice
PASSIVE - Successfully Hitting an Enemy God with a Critical Strike will subtract 3s from all of your abilities currently on Cooldown, except your Ultimate ability. This effect can only happen once every 5s.

Wind Demon
PASSIVE - Your Critical Hits provide you with 10% Physical Penetration and increase your Attack Speed and Movement Speed by 20% for 5s.

Thickbark Acorn
PASSIVE: When Ratatoskr deals damage with an ability he restores 3% of his Maximum Health. Flurry now provides protections equal to the protections shred from enemy gods. Flurry gains an additional charge.

Gladiator's Shield
PASSIVE - When damaging an enemy god below 60% health with an ability you deal an additional 15 + 25% of your Protections from items and abilities. Can only trigger once per enemy per ability.

Mantle of Discord
PASSIVE - If you take damage below 30% health you unleash a shockwave that stuns all enemies within a range of 20 units for 1s and become immune to Crowd Control for 1s. This effect cannot trigger more than once every 90s.

Ancile
PASSIVE - Whenever you take Magical Damage from an enemy ability you unleash a shockwave that Silences all enemies within a range of 30 units for 1s. This effect cannot trigger more than once every 30s.

The Crusher
PASSIVE - Enemies hit by your damaging Abilities take an additional 20 Physical Damage + 15% of your Physical Power over 2s.

Heartseeker
PASSIVE - Your abilities deal an additional 2% of the targets maximum Health as Physical Damage. If you have over 200 Physical Power, your ability bonus damage scales up. This effect reaches a maximum of 5% Maximum Health damage at 400 Physical Power. Subsequent hits on the same target do 75% bonus damage for the next 3s.

Thistlethorn Acorn
PASSIVE: Enemies hit by Acorn Blast are debuffed, taking 5% additional damage from Ratatoskr's abilities, stacking up to 3 times. Acorn Blast now fires 5 Acorns.

Transcendence
PASSIVE - 3% of your Mana is converted to Physical Power.

Jotunn's Wrath

The Crusher
PASSIVE - Enemies hit by your damaging Abilities take an additional 20 Physical Damage + 15% of your Physical Power over 2s.

Arondight
PASSIVE - When your Ultimate ability has finished casting, reveal all enemy gods within 120 units for 8s. While moving towards revealed enemies gain 30% Movement Speed. When first striking a revealed target they take an additional 40 + 30% of your Physical Power. This can only occur once every 45 seconds.

Heartseeker
PASSIVE - Your abilities deal an additional 2% of the targets maximum Health as Physical Damage. If you have over 200 Physical Power, your ability bonus damage scales up. This effect reaches a maximum of 5% Maximum Health damage at 400 Physical Power. Subsequent hits on the same target do 75% bonus damage for the next 3s.