An <code>Effect</code> is what handles the specific logic on the entity it is on. For example, <code>Effects#SPEED</code> adds an attribute modifier that affects the movement speed while <code>Effects#WITHER</code> attacks the entity from a <code>DamageSource</code> whenever the potion effect is ready to be applied.
== Creating an <code>Effect</code> ==
You can create an <code>Effect</code> using two methods. The first creates a regular <code>Effect</code> and applies the logic in some event method. The other method involves extending the <code>Effect</code> class and overriding specific methods when needed. This documentation will focus on the second method.
There are four methods that are important depending on the type of effect you are creating. In each scenario, you should take into account whether you should extend <code>Effect</code> or <code>InstantEffect</code>.
Here are the classes and methods to review:
{| class="wikitable sortable" border=1
!Class !!Usage
|-
| <code>Effect</code> || The basic effect class. Should be used if the effect happens over time.
|-
| <code>InstantEffect</code> || An extended version of the effect class. Should be used if the effect happens only once and instantly.
|-
|}
{| class="wikitable sortable" border=1
!Method !!Description
|-
| <code>isReady</code> || Determines how fast an effect should call <code>performEffect</code> while applied. This is overridden by <code>InstantEffect</code> to occur after one tick. If too fast, the server will not have enough time to execute the damage on the entity.
|-
| <code>performEffect</code> || Executes the logic on the entity when called.
|-
| <code>isInstant</code> || Determines if the effect is instant. Returns true in <code>InstantEffect</code>.
|-
| <code>affectEntity</code> || Executes the logic on the entity when called. <code>isInstant</code> must return true for this to be called.
|-
|}
If you are only modifying an entity <code>Attribute</code>, then there is no need to extend the class. When constructing the effect instance, chain <code>addAttributeModifier</code> and select the specific attribute, it's unique id, the amount to affect by, and the operation to apply the amount with.
Effects need to be [[Registration|registered]].
== <code>EffectInstance</code> ==
To allow greater customization, each effect is passed in as an <code>EffectInstance</code> which allows the user to specify additional information for what the effect should do.