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You have the wrong version see: https://gitlab.com/scs_torleon/libraryferret/-/issues/10

You are missing a mod depdendency see https://www.curseforge.com/minecraft/mc-mods/awesome-dungeon-forge

You can get the collision shape of a block using the BlockState#getCollisionShape method. You can then call the isEmpty method on the result, and if is true it means that the block you get the collision shape from has no collision

If it helps, I did something similar recently. This is the overlay class, implementing IIngameOverlay: https://github.com/Syrikal/alchemine/blob/main/src/main/java/syric/alchemine/client/VitaSlimeOverlay.java Here's my overlay registry class, which triggers at the same time I register blocks and items and whatnot: https://github.com/Syrikal/alchemine/blob/aae585ab7d23fd4be688a60642f200ab09a4fe38/src/main/java/syric/alchemine/setup/AlchemineOverlays.java And here's where I turn the overlays on and off (it's triggered by RenderFogEvent because it happens concurrently with some fog stuff, but this is a little hacky.) https://github.com/Syrikal/alchemine/blob/47d9d08a092d3e26441bace8fb5014db0c78c332/src/main/java/syric/alchemine/client/FogEffects.java

It looks like you really want to know when an entity is attacked from your code? You might be able to do some tracking yourself with forge's LivingHurtEvent and looking at the DamageSource. Maybe storing the state using a Capability on the entity?

Entity.horizontalCollision is for colliding with blocks. Minecraft doesn't really do entity/entity collision, except in special cases like item pickup. Those are not events with state stored in the entity, its a special process that uses one of the level.getEntities() search methods. Those won't be appropriate to call during rendering.