Waves

Since the next release. WaveAbility is a wave that rises in front of its user and runs ahead of him: mud, water, sand.

It leaves from his feet along where he looks, flat, waveSpeed() blocks a tick (1 by default) for runTicks() ticks, halfWidth() blocks to each side. Every body it reaches is hit waveDamage() real HP, once, and carried along with it. The direction is taken as it leaves: turning afterwards does not steer it. The cooldown starts when it has run.

public class MudWaveAbility extends WaveAbility {

    public MudWaveAbility(AbilityCore<MudWaveAbility> core) {
        super(core);
    }

    @Override protected int runTicks() { return 10; }
    @Override protected double halfWidth() { return 2.5D; }
    @Override protected float waveDamage() { return 20.0F; }
    @Override protected float waveCooldown() { return 240.0F; }

    @Override
    protected boolean mayHit(LivingEntity user, LivingEntity target) {
        return AkumaTargeting.isEnemy(user, target) && AkumaProtection.canUseAbilityAt(target, this.getCore());
    }

    @Override
    protected void onWaveStart(LivingEntity entity, Vec3 crest, Vec3 heading) {
        if (!entity.level().isClientSide()) {
            entity.level().addFreshEntity(new MudWaveEntity(MyEntities.MUD_WAVE.get(), entity.level(), crest, heading, this.runTicks() + 1));
        }
    }

    @Override
    protected void onWaveHit(LivingEntity entity, LivingEntity target) {
        target.addEffect(new MobEffectInstance(MobEffects.MOVEMENT_SLOWDOWN, 80, 1), entity);
    }
}

Hook	When	For
mayHit(user, target)	each body under the crest	the fruit's rule on who is an enemy, and the target's own protected area
onWaveStart(entity, crest, heading)	as it leaves, both sides	the entity that shows it (server side), sounds, the user's animation
onWaveHit(entity, target)	a body it struck, once, server side	what the element does to it
onWaveTick(level, entity, crest, side)	each tick it runs, server side	what it leaves on the ground, its spray

wavePush() and waveLift() set how hard a struck body is carried along (1.3 and 0.4 by default). crest() and heading() give where it is and the way it runs.

The wave is not drawn by the library: your entity, spawned in onWaveStart, runs at the same speed for the same time.