You can get 625 fragments from the Event, and you can go back and get all the fragments if you strategize well enough. So you only need 375 total from Challenges.
Pass estimate for Manticore is between 4000 passes (if you win the bad luck lottery and only get 18 fragments per Challenge) and 1800 passes (if you used some sort of ritual to get the maximum possible fragments). I'm going to assume it's about 2800-3200 pass.

Here it is, guys! Ladybug (or Ladybird) is coming along with Hippidion!

Isn't this like the second time prehistorics are making a comeback within a year, I feel like I just completed my collection

The Chimera Fragment Lucky Chest like Gorilla...

I hope you guys are right about Hippidion being in the HOPs...I have a small stash saved up, and so may go for her since she gives tears on a predictable schedule. I already have all of the prehistoric divines, but could always use more tears! I will be going for the chimera as well, to keep my collection/trophy complete. Even though I hate having to shell out so much equus to tame them, and its annoying how they continually refuse care, even after being tamed. I wish they continued giving passes after age 80 too.

Profile
Name: Manticore
Type: dragon divine
Number of lives: 4
Item: TC (lvl 7)
Perk: gives you a random dragon pet after you fill it's meter
Drop rate: (still gathering the patience to test this)

Fragments:
-Total number of fragments in promo:
--625

-Number of fragments needed *IF* you collect ALL the fragments from the promo:
--325

-Number of fragments that you'll find in the promo even if you try not to go for fragments:
--325 fragments (this forms a part of the 625 total fragments that can be found in the promo. Do not expect to get all 1 000 fragments from the promo because that is not possible.)

Average fragments per TC:
-(without 2× bonus) 9-19 fragments (I died mostly on level 4-5)
-(with 2× bonus) 18-38 fragments.

*The 2× bonus for this promo CANNOT be unlocked with a community objective. It can only be unlocked by progressing in the event.*

Also, no, there is no 3× bonus for this promo.


Cost:
-10000 to 14 000 passes (50-70 TCs) (average) (0× bonus + bad luck + 0 fragments from the event/empty fragment bar) to fill the meter IF you get the rest of the fragments somewhere along the line
OR
-22 400 passes (112 TCs) (0× bonus + min 9 fragments per TC + 0 fragments from the event/empty fragment meter) to fill the meter
OR
-1 800 passes (9 TCs) if you get max fragments per TC with the 2× bonus (AKA min price with bonus assuming that you got ALL the fragments in the event)
OR
-3 800 passes (19 TCs) if you win 18 fragments per TC with the 2× bonus (AKA max price with bonus assuming that you got ALL the fragments from the event)
OR
-11 200 passes (56 TCs) to fill the meter from 0 with the 2× bonus assuming that you win the minimum 18 fragments per TC and you don't win the divine along the way (AKA max price to fill the meter from 0 with the 2× bonus)

Average price that you can expect for the divine if you try to win it from the TC with the 2× bonus:
-2 000 to 4 600 passes (10 - 23 TCs), assuming that you collected most of the fragments from the event

-The general price range is anywhere from 1800 passes (9 TCs) (if you get max fragments per TC but you don't get the rest of the fragments along the line and you only try to get him after you get the 2× bonus), to 22 400 passes (112 TCs) (if you are very unlucky and you try to get him without the 2× bonus and you don't get the leftover fragments anywhere along the line). You can expect to pay anything in between these values, and how much you pay depends entirely on whether you try to get him with the bonus and your luck with the TC. And if you're REALLY lucky, you may even get him in your first TC for only 200 passes.

How your dragon's health bar works:

-Your dragon has 2 health bars: one for the lives that it regenerates and a SEPARATE SECOND BAR for the lives that you bought.

- Your dragon's regeneration health bar is the white bar on the top left of the event screen. Every time you attack a monster, you use up a certain amount of health points from your dragon's health bar. The heart next to your opponent's head with the ×1, ×2, etc written on it indicates the amount of health points that are used up PER ATTACK made on that specific monster. So if it says '×3' then your dragon uses 3 health points per attack made on the monster and so your dragon's health bar will decrease by 3 points every time you attack that specific monster. If you do not have sufficient lives with which to attack the monster, the game will prompt you to buy lives and you will not be able to attack until you regenerate or buy sufficient lives.

- When buying lives, the lives are NOT ADDED TO your WHITE HEALTH BAR. Instead, they get added to a SEPARATE health bar that is represented by the red heart to the left of your white health bar. So if you buy 4 lives, the number next to the red heart will increase by 4. When attacking, your dragon uses health points from it's white health bar first. After those points run out it will start using health points from the second health bar.


How your opponent's health bar works:

- Your opponent's health bar is yellow. It has a number written on each side of it. The number on the right indicates the total number of attacks are needed to defeat that monster and the number on the left indicates how many remaining attacks are needed to defeat the monster.
--Eg. If you attack a monster with a health bar (3-- health bar --3) once, then the number on the left will decrease to 2 because you need to make 2 more attacks to defeat the monster, but the number on the right will stay 3 because it's the total number of attacks needed and it's not going to change. So your opponent's health bar will look like this afterwards: (2-- health bar at decreased amount --3)

Number of lives needed during the promo:
*this number will vary from player to player based on the order in which you upgrade your dragon's stats, how often you stray from the path to get gifts and whether or not you use up your dragon's attacks before it's health bar gets full and stops generating new attacks (you waste potential attacks every time your dragon's health bar stops regenerating lives)*
-price of 4× lives = 90 passes (this cost may be halved during a lives sale or the number of lives will be twice as high during a lives sale. And the lives sale is most likely going to be over the last 1-2 weekends of the event.)
- 348 lives needed to rush through the promo (if you stray from the path often to get gifts but not fragments. It costs 7 830 passes)
-It costs about 630 passes (28 lives) to go through the promo again to win the leftover fragments.

Upgrades:
-The first upgrade that you should make is to shorten your dragon's regeneration rate. Unfortunately, it will be a bit costly and it will take a bit longer to collect the necessary elixir, but it will be worth it in the long run.

-The next upgrade should be either to your dragon's regeneration rate or your dragon's attack power. DO NOT UPGRADE YOUR DRAGON'S HEALTH BAR SIZE UNTIL YOU NEED TO UPGRADE IT. It may be a cheaper upgrade to make in the short run, but it will not benefit you much in the long run. This is because it is uses up the elixir that you need to upgrade your regeneration rate/attack power so what you are actually doing by upgrading your dragon's health bar is preventing your dragon from regenerating attacks faster and preventing your dragon's attacks from growing stronger. Do not do that. Its just a bad idea.

-When you should upgrade your dragon's health bar size: only upgrade it when you reach a point where your dragon is regenerating lives so quickly that your dragon's health bar becomes full overnight while you're sleeping. Or if you have elixir to spare. Why? Because every second that your dragon does not spend regenerating lives counts as a second that is wasted. So you end up 'losing' or wasting potential attacks if your dragon's health bar is full.

Misc.
-The final prize of the event is a companion that offer a +10 bonus for stamina.

-You get to choose which door you want to go through when there are multiple doors in a room. When you make this choice, consider both the benefits of the gifts that you will get and the amount of health that it will take to defeat a monster to choose which door is best for you.

-Make a decision as to whether or not you want the divine BEFORE you start the promo. This will help you choose which door is best to use later in-game because of the all the fragments that can be found in the promo.

-When going through a door that will give you an objective, do NOT expect a gift. Objective doors do not offer gifts, and you will still need to defeat the monster AND complete the objective/wait the required time before you can get through the door. Whereas for the prize rooms you just need to defeat the monster and you can move through. And you get a gift.

-You can collect multiple gifts in each room by defeating the monsters that are guarding the respective doors. But as soon as you choose to go through a door, you cannot turn back and collect more gifts from the previous room(s). And thus you lose the ability to collect the gifts until you finish and replay the promo.

-Each door leads to the same room, so there's no need to worry about choosing a 'correct' path through the event.

-The event offers pass seeds as a prize, but there are not enough seeds for a full meadow. A maximum of 14 seeds can be found in the event.

-You can replay the promo to collect the leftover gifts, but you cannot collect the final prize more than once and you cannot collect gifts that you have already collected. Each gift can only be collected ONCE unless it is offered multiple times during the event.

According to the Lowadi Twitter feed, the Chimera horse will be in the Challenges, while Hippidion will be in the Horns of Plenty.

The average price you're looking at is anywhere between 200 and 12000 passes. This can be offset by gathering fragments along the way.

If you gather the maximum 625 fragments, you're looking at an average expense of about 1800-3600 passes, depending on your luck