Been a while, but I thought I'd make another discussion page to help clear some stuff up and mention a couple of things that might be handy to know for the mod.

To start us off, remember that for the mod to fully work, you need all 3 parts of the mod, this mod and the other 2 mods, subbed. If you don't, it might not work right. Second, the mod doesn't work well that alters the final bosses, as every boss has their own coding and sprites, so if things break, be sure to check which might have been causing problems. The exceptions that I can think of the top of my head would be the Eternal Champions mod made by TheEvilPickle, as it was made to be compatable with that version specifically, and Piber's Gameplay Rebalance mod, which only changes the light attacks for the Isaac/Blue Baby fights and have been made compatable with HMMBP.

Now, lemme just touch up on one thing before getting into tips with the mod: The workshop is pretty wonky with how it functions, and with big mods like Revelations and Community Remix Remixed, sometimes download failures happen. When it does happen, some stuff might not be there or some coding that is important will not be where it should be. This is more of a problem with the Steam Workshop than the mod itself. For the most part, anyway. If you run into problems, it always helps to redownload the mod. It doesn't hurt to report the problem anyway, but it helps to do some checks and balances to be sure if its the mod's fault or its the Workshop just being dumb with downloads. I mention this now cause I know people who play Revelations and CRR go through these problems quite a bit and have to keep repeating this same answer a lot, and this mod also suffers the same problem.

Now, let's get to a little introduction of the mod, since the description and name is a little vague. Hard Mode Major Boss Patterns adds changes to the final bosses of the game. To specify, the bosses that give an ending are the ones that are augmented, such as Mom, Mom's Heart, It Lives, ect. The normal bosses are left unchanged. The mod's changes to the bosses, without getting too detail-y, are:
-New attacks
-Changes to existing phases
-Additional phases and forms
-Health scales to your damage, similar to Revelations but on a much simpler scale
-New enemies for some bosses
These changes only take place if you have the run set to Hard Mode and Greedier Mode. If you play on Normal Mode or Greed Mode, the changes will not take place.

I won't spoil everything there is to this mod to offer, but I will at least give some pointers for some noteworthy parts that could warrent an explanation for people confused about some stuff.

1. Once Mom reaches 50% health, she will perform a series of very quick stomps. The first stomp will act as normal, aiming for your current location, but the next 5/6 stomps are different, where she will lead her shots, aiming for where you will go if you keep going in one direction. One way to avoid getting hit is to go in one direction, then with proper timing, change directions to avoid taking damage. It takes a specific rhythm to do it this way, however. An easier option is to simply do a small doughnut around the room, going in a circle. If you aren't confident or are just getting grips on the motions, do this until you have her rhythm down.

2. One of Delirium's changes is that depending on what transformation you have when you fight him, he will have new attributes to his fight. Not every transformation does something, but here are the ones that do affect him:

-Leviathan: When Delirium transforms, a black ring aura will sometimes appear above Isaac.
After a couple of seconds, a ring of black tears will appear with the same range as the ring.
-This attack is borrowed from The Lamb 2.
-He also gains a new move where he'll spawn a large Black Heart that acts as a shot blocker.
-Once destroyed, it will release tears in the 8 cardinal directions.
-Seraphim: Passively shoots out a line of Crack in the Sky lights in a straight line at you.
-Beezlebub: Gives Delirim 2 Delirium-like fat flies orbiting slowly around him, around the same
size as the Fat Flies you get that act as shot blockers.
-Adult: Gives Delirium more health
-Stompy: Every time Delirium transforms, a 3 ring shockwave will be created around him. Additionally, he will gain a new attack where he'll produce 3 stomp noises, and then release shockwaves in a + pattern.
-Conjoined: Delirium will have 2 tumors on the left and right side of his cheeks that will
periodically shoot diagonally from where he is currently facing, similar to when you have it.
-Yes Mother: giant knives will periodically fall down from above, similar to Mom's last ditch phase.
-Fun Guy: Delirium-skinned Mushrooms will spawn around the room as Delirium takes damage.
-Previously, it would create short-range floaty cluster shots around Delirium as he takes a
certain amount of hits, like spores.
-Spider Baby and Oh Crap: Similar to Fun Guy, spawning spiders and Delirium-skinned Dips
around him when he takes a number of hits.
-Bob: Delirium passively leaves creep around him.
-Spun: All of Delirium's shots, including shots fired when transformed will behave erratically,
wavering around randomly and some tears being Continuum shots.
-While troublesome, this also can work to your advantage since some of his shots can avoid
you completely.
-Bookworm: The Delirium projectiles he fires have a chance of being fired in a fork pattern.
-Guppy: The Delirium projectiles will spawn attack flies when they land

3. On the topic of Delirium, his new phases added in mirror the intro narration. Remember this.

4. Ultra Greed and Greedier both get changes if played on Greedier, so try them out too.

I will make more notes when I have time. Until then, I hope this helps, and have a pleasant day!