Combat mechanics

The combat mechanics of Doctor Who: Legacy involve matching colored gems in combination with the abilities of a team of characters. Combat is turn-based, allowing the player to take his or her time making a move. To make a move, the player selects one gem on the board and drags it around the board for a short period of time, swapping it with other gems as it moves.

Combos

A combo is a group of gems composed of horizontal and vertical lines of three or more gems of the same color in a row. After the player makes a move, all combos on the board will be cleared away; any empty spaces on the board are replaced by gems from above (new gems will also fall from above), then any new combos on the board are cleared, and this process is repeated until no new combos form. Any characters on the player's team that match the color of the combos will get an attack for the turn; a combo of pink gems causes the player's team to gain health based on its combined Heal attribute. If five or more gems are cleared in a single combo that triggers an attack, attacking characters of that color will attack all enemies.

The strength of an attack for a given character is based on its ATK attribute. A group of three gems matching a character's color results in that character getting an attack strength equal to the character's ATK. Each additional gem cleared in a single group of gems adds 0.25 of the character's ATK to the attack strength. The same is true for healing, except it uses the team's combined Heal attribute instead of a character's ATK.

If multiple combos are made in one turn, each additional combo beyond the first made in that turn will add an 0.25 combo multiplier to the strength of each character's attack, as well as to the amount of health gained by matching pink gems.

Character types

Main article: Character types

Depending on the characters' base attributes, DWLegacy Wiki classifies each ally character as one of four different types: tank, offensive, healer or balanced.

Character powers

Main article: Character powers

Character powers can be used to influence combat outside of attacking, such as by changing the colors of gems on the board or by inflicting the poison condition. Both ally characters and enemy characters can use powers.

Gem colors

Main article: Gem colors

The damage dealt by an ally character's attack is affected by gem color affinities. An ally character deals twice as much damage when its color is strong against the enemy, while it deals half as much damage when its color is weak against the enemy. When targeting an enemy, arrows will indicate for any allies whether their attacks would be strong or weak against that enemy.

Damage formula

The damage formula for a given character's attack versus a given enemy is as follows.

${\text{damage}}=a*(1+[N-1]*0.25)*ATK*\sum _{m\in M}[(1+[g-3]*0.25)*(1+b*0.1)]-R$

Where a is the affinity multiplier (2 if the gem color of the attack is strong against the target, 0.5 if it's weak) and N is the total number of combos made that turn. The summation represents the sum for each combo m over all matching combos M, where for each combo m, g is the number of gems in the combo and b is the number of boosted gems in the combo. Finally, R is an enemy-specific value which reduces damage dealt to that enemy by each attack by a constant amount (for many enemies, this value is 0); this damage reduction can't reduce the damage an attack deals to less than 1.

For example, a turn in which two blue combos are made (and no other combos), one with 4 boosted gems and another with 3 unboosted gems, the summation would yield the result 2.75: the first combo has a multiplier of 1.75 (1.25*1.4), and the second has a multiplier of 1. A blue character would then have an attack strength of approximately 3.44 (2.75*1.25) times its ATK, and the damage dealt to the enemy would be that attack strength modified by the appropriate affinity multiplier and potentially reduced by some amount for that specific enemy.

Against single enemies, this often means maximal damage output can be achieved by making many small combos of three gems rather than fewer large combos. For instance, two combos of three gems in the same color yield a final multiplier of 2.5 (1.25*2), whereas a single combo of seven gems yields a multiplier of only 2 (1+0.25*4). Intuitively, this is explained by the fact that each gem in a combo of three gems contributes one-third of the character's ATK, whereas each additional gem only contributes one-fourth, in addition to the higher combo multiplier obtained by matching more combos.

Notably, damage reduction is applied to attacks on a character-by-character basis; for instance, an enemy that takes 1000 less damage from attacks (R value of 1000) will take 2 damage (1+1) from two characters with neutral affinities who attack for 800 each, rather than 600 (had the reduction been applied to the total damage).

In rare instances, a gem with a color associated with attacks can be weakened. Currently this can only occur if an enemy's convert power converts weakened pink gems to another color; in those cases, a modification is made to the damage formula analogous to that part of the healing formula.

Healing formula

The healing formula is similar to the damage formula, except it uses the team's combined Heal attribute. The formula is as follows.

${\text{heal}}=(1+[N-1]*0.25)*Heal*\sum _{m\in M}[(1+[g-3]*0.25)*\max {(0,1+b*0.1-w*Q)}]$

Where, similar to the other formula, N is the total number of combos made that turn, and the summation represents the sum for each combo m over all matched combos of pink gems M, where for each combo m, g is the number of gems in the combo, b is the number of boosted gems in the combo and w is the number of weakened gems in the combo. Finally, Q represents the percentage by which the enemy's power reduces a combo's health gain for each weakened gem used in it; this number varies for different weaken powers.

Notably, a gem can be simultaneously boosted and weakened. If so, it will count for both the boosted and weakened gem counts in the formula above. Multiple boosts and multiple weaken powers have no additional effect, but a weaken and boost power are additive; since most weaken powers have Q-values with greater magnitude than 0.1, such gems will display minus signs, though they won't be weakened as much as if they hadn't been boosted. For instance, if a weaken power has a Q-value of 0.5, a gem affected by that power and a boost power in a combo has a multiplier modifier of -0.4; so if it's used with two unaffected pink gems in a combo, that combo has a multiplier of 0.6 (1-0.4).

Similar to attacks against a single enemy, maximal healing is achieved by matching many small combos of pink gems rather than a large combo of many pink gems. That effect is significantly increased by the presence of powered-down pink gems.