Attack and Defense is a core concept in SMITE.
Damage[ | ]
Damage is what attacks and offensive abilities cause on enemy targets. When a unit (be it player controlled gods or computer controlled minions and jungle monsters) takes damage, it will lose a certain amount of health. If the unit loses all of their health they will die, rendering them unable to continue fighting (gods will respawn after a set amount of time).
Damage can be dealt as a specific value, or as a percentage of the target's current or maximum health. There are also certain effects called Damage over Time (or DoT) that instead of dealing their damage as soon as they are applied, they will instead do small ticks of damage over its duration.
There are three types of damage in the game: Physical, Magical, and True damage. Physical damage can be mitigated by physical protection, and magical damage can be mitigated by magical protection. True damage deals its full amount regardless of how much physical or magical protection the target has. Gods are classified as being either 
Magical or 
Physical, with their attacks and abilities applying the matching type of damage. True damage is relatively rare; an example is Bakasura's Butcher Blades ability or Serqet's Last Breath ability.
Damage reduction is a mechanic that lowers the damage output of the afflicted god or unit by a number of percentage. It can either affect a single type of damage or it can affect all types of damage, including True damage. The inverse of this is damage increase, which will boost damage dealt with one or any type of damage. For example, 
Sundering Spear increases all damage the affected target takes.
There are rare circumstances where gods can apply damage of a different power type than their own. For example, 
Mystical Mail has an aura effect that deals magical damage around the user and can be acquired by physical gods.
Power[ | ]
Gods have a "Power" statistic which attacks and abilities scale from, increasing their damage output. Most gods start with 0 power (an example of an exception is Kukulkan whose passive ability grants him magical power equal to a percentage of his maximum mana) and can gain power from items and some god ability effects. Certain jungle buffs can also increase a god's power.
Basic Attacks[ | ]
Unlike in most other games in the genre, basic attacks are skillshots (projectiles that move in a straight line with a travel time or area attacks with a delay) with most 
Ranged gods firing projectiles that move in a straight line while 
Melee gods deal damage to the closest enemy within range. Basic attacks scale based on the god's level and their Power stat. The "Basic Attack" number indicates the amount of unmitigated damage a basic attack does. Each god has a formula that defines what their Basic Attack value is. The formula for how basic damage is calculated is:
Base Damage + (Base Damage per lvl × God's lvl) + (100% of Physical Power OR 20% of Magical Power)
With few exceptions, all magical gods scale at 20% of their Magical Power, and all physical gods scale at 100% of their Physical Power. The exceptions to this rule are Izanami, a hunter who has boomerang-like basic attacks that go through targets and that scale at 75% Physical Power when fired and 35% while returning to her, and Olorun, a mage who's basic attacks have a 25% Magical Power scaling.
Buffs and effects that grant a percentage basic attack damage increase will apply the bonus before the physical/magical power contribution.
Attack Speed defines how many attacks a god can fire per second. The higher the value is, the sooner a god will be able to reuse their basic attacks. Bake Kujira, Jormungandr and King Arthur are the only gods whose basic attacks are not affected by attack speed.
Some gods have a hit progression which affects the swing time (the delay before a basic attack is actually fired) and amount of damage a basic attack does, and in some cases even granting them an additional effect. A good example of this is Ne Zha, who has a 4 stage basic attack progression where the first two attacks deal 100% damage with normal swing time, while the third attack has a 150% damage and swing time, finishing with a 200% damage and swing time attack that affects all enemies in an area in front of him.
Physical gods have access to Critical Chance, which gives them a chance to land critical strikes with their basic attacks. Critical strikes deal 175% of basic attack damage as a regular basic attack. The item 
Deathbringer increases how much damage critical strikes do by an extra 30% (205% total).
Launching a Basic Attack while moving will apply a movement penalty that reduce movement speed by 50% for ranged gods and 35% for melee gods (The movement speed counter will not change while doing so). The "Haste" passive effect of items such as 
Hastened Katana and 
Hastened Ring removes this movement penalty on activation.
Abilities[ | ]
Similar to basic attacks, the majority of offensive abilities are skillshots that must land on a target for them to have any effect. Some can be projectiles, while others are either Area of Effect (AoE, an attack that affects a specified area) or Line attacks (similar to AoEs, but they originate from the caster). Some abilities can even be a mix of two or more of these types (For example, Hel's Decay is a projectile that goes through minions but explodes on contact with an enemy god, dealing damage in an AoE). Additionally, there are some abilities that require the caster to lock onto specific targets or that automatically aim at valid targets within range.
Most damaging abilities have a base amount of damage (which may increase each time a skill point is put into the ability), plus an additional amount based on the god's Power stat. For example, Ra's Celestial Beam at max rank will do (335 + 100% of Magical Power) unmitigated damage. Some abilities may also scale with other stats such as Basic Attack Power, which is equal to the damage the god currently deals with their basic attacks, or Health.
There are a few abilities in the game, like Mercury's Made You Look and Serqet's Deathbane, that can be affected by Critical Chance, which is normally something that only affects basic attacks.
Healing[ | ]
Healing is an effect applied by certain abilities and items and acts as the opposite of damage. When a god or unit is healed, they will recover a certain amount of their health up to the maximum health cap. Any healing done beyond the cap (also called Overhealing) will generally do nothing and go to waste. The most common way of healing is with the item 
Healing Potion.
Just like with damage, healing can either restore a specific amount or a percentage of the target's current/maximum health. Healing over Time (usually called Regeneration or Regen) also exists, restoring health in ticks over the buff's duration rather than all at once.
All units will naturally regenerate health over time based on their HP5 (Health per 5) statistic, which shows how much automatic healing they'll receive over 5 seconds. Lifesteal on the other hand is a statistic that causes any damage by a god's basic attacks (and abilities for magical lifesteal) to heal the god by a portion of the damage dealt.
Players can counter healing with Anti Healing, which reduces the amount of healing the victim deals and/or receives. Certain god abilities apply this effect, but the main way of acquiring this effect is through items such as 
Toxic Blade. A list of anti healing items can be found here: Healing Reduction items.
Protections and Mitigation[ | ]
Protections and mitigation alleviate the impact of incoming enemy attacks and abilities on the victim's health, which can prevent (or at least delay) their death.
A god's magical and physical protection values will reduce the amount of damage the corresponding types of damage apply. A god's inherent protections scale with level. For example, Ymir's total physical protection is 32 + 3.5 × level + Physical Protection From Items. Ignoring penetration for now, the formula for how a protection value reduces damage is:
Damage = (100 × Unmitigated Damage)/(Protections + 100)
The result of this equation means that a protection value of 50 will reduce damage by 33%, 100 will reduce it by 50%, and 150 will reduce it by 60%.
For example (still ignoring penetration), if Ra's Celestial Beam is listed as doing 335 damage, and he hits someone with 70 magical protection, then the actual damage will be 197 = ((100 × 335)/(70 + 100)).
Damage can also be mitigated by percentage damage reduction like Athena's Defender of Olympus. Percentage damage reduction stacks up, can't be penetrated by any means and, unless otherwise stated, will affect even True damage.
Some abilities and items, like Geb's Hard as Rock passive or 
Spectral Armor, can lower the amount of extra damage dealt by critical strikes.
As the majority of abilities and attacks in this game are skillshots, they don't lock on targets and can be dodged if the victim moves out of their way, completely nullifying any damage (or healing) the projectile could have done. This makes aim and quick reaction timing something critical in SMITE that can and will define a victory or a loss regardless of the damage or defense of either player.
Penetration and Reduction[ | ]
Penetration and reduction help counter an enemy's defenses, increasing the efficiency of attacks and offensive abilities.
A target's protection values can be lowered or bypassed with certain items and abilities that grant penetration and reduction effects. They are (in order):
- Percent Reduction. This will reduce a target's protection values by a percentage. For example,
The Executioner will reduce a target's physical protection by 7% per hit, up to 28%. - Flat Reduction. This will reduce a target's protection values by a specific amount. For example, Stone of Binding will reduce a target's physical and magical protections by 0.8 per level.
- Percent Penetration. This will ignore a target's protection values by a percentage. For example, Heartseeker will ignore 10% of a target's physical protection.
- Flat Penetration. This will ignore a target's protection values by a specific amount. For example, Jotunn's Wrath will ignore 10 of a target's physical protection.
Thus, to determine the actual protection values of a target, the equation is:
Actual Defense = (Protection × (1-%Reduction) - Flat Reduction) × (1-%Pen) - Flat Pen
Percent penetration is capped at 40% while Flat penetration is capped at 50. The protection values cannot go below zero.
Example[ | ]
An example of a highly unlikely build with the items mentioned before:
- The Executioner + Glyphs: +7% Reduction per stack
- Stone of Binding: +0.8 per level
- Heartseeker: +10% Penetration
- Jotunn's Wrath + Glyphs: +10 Penetration
This god is level 20 and has a Basic Attack value of 105. Fighting against an opponent with 238 physical protections, (and ignoring any of the items' additional effects) the first basic attack will do:
Actual Defense = (238 × (1-.0) - 0)) × (1-.1) - 1 = 213.2 Actual Damage = (100 × 105) / (213.2 + 100) = 33
Now that a The Executioner stack is applied and assuming Stone of Binding was activated with the last attack, the next basic attack will do:
Actual Defense = (238 × (1-.07) - 25)) × (1-.1) - 1 = 175.706 Actual Damage = (100 × 105) / (175.706 + 100) = 38
And the next basic attack now with 2 The Executioner stacks:
Actual Defense = (238 × (1-.14) - 25)) × (1-.1) - 1 = 160.712 Actual Damage = (100 × 105) / (160.712 + 100) = 40
And the next basic attack now with 3 The Executioner stacks:
Actual Defense = (238 × (1-.21) - 25)) × (1-.1) - 1 = 145.718 Actual Damage = (100 × 105) / (145.718 + 100) = 43
And the final basic attack now with 4 The Executioner stacks:
Actual Defense = (238 × (1-.28) - 25)) × (1-.1) - 1 = 130.724 Actual Damage = (100 × 105) / (130.724 + 100) = 46