This guide might be one of the urgent and highly requested ones as to help you decide What-To-Get from the upcoming seasonal event shop.
As this is prior to upcoming events, I'll be focusing more on this guide for now, and extend more time later on to finish developing my other guide on "Hidden Potential".

Special thanks to Tombola for the screenshots; you can check upcoming events from his post in this link:
http://community.gtarcade.com/forum....ge%3D1&page=21

Q1. The first important question you might have in mind is what are there so many items for this event?
A1: Every seasonal event plays with 5 different items. 3 keys for opening chest draw reward and 2 different shop currency.
In this case we have:
3 keys for chest draw - Normal Shell, Fine Shell, Rare Shell
2 Shop currency - Starfish (S), Starfish (L)

Keys used for chest draw will give a varying type of prize as shown below in this screenshot:

Attachment 9518

As you can see the 3 types of keys also are of different quality to yield different amounts of prize.


Q2. How to rake up more shop currency (starfish)?
A2: Generally, there are up to 5 possible ways to gain shop currency.

#1 - hot event tasks. This is one of the reliable ways of getting more shop currency
Attachment 9519
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Attachment 9525

(highlighted are the tasks that can be done with some effort and time)

#2 - drawing from the event chest. I know this is unreliable as it suggests with the probability of drawing starfish (S) and (L) are 1/8 respectively from
all the possible chest reward. Yet, chest draw often yields the most in getting your shop currency compared to the other viable sources, as more often
chest keys are always more attainable and available than shop currency. I recommend using 10x draw whenever possible, as early in the few days when the event begins,
to get some extra rewards for doing so:
Attachment 9521

#3 - killing epic and legendry mobs in elemental zone often drop starfish(S) more often than starfish(L)

#4 - world and point rewards in event menu. This is definitely the most reliable way, and should also be yours too, for getting more shop currency.
Reaching the required point benchmark will reward you with bonus amount of shop currency that you can use later. Very rewarding indeed

Attachment 9522Attachment 9523

#5* - consume resources event. This event appears usually on the last 3 days before seasonal event ends. What you need in preparation are:
at least 1.8k blessed stones and 8k soulstones in order to effectively collect all 3 different quality keys. As soulstones is at a greater demand,
I do understand that it will be a constrain on resources, thus 8k soulstones should be enough to get rare shells at least twice during this event period.
After attaining more chest keys, this will again fall back unto the draw-and-pray for shop currency reward in chest draw (see #2)

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*this guide will be subjected to correction over time to provide you with the most accurate information on the topic of discussion*