The Astral Emblem introduced in TFT Dragonlands has become of the strongest emblem across the famous auto-battler, as it has turned many 5-cost units into a 3-star, but does it always work like that?
The way to do it is also quite easy. The first thing is to 3-star all other Astral units. Once that has been done, place the Astral Emblem onto the 5-cost unit you desire then every 5 rolls in the shop, the Astral shop will appear with that 5-cost champion.
How Astral works in TFT Dragonlands
According to lead designer of TFT, Riot Mortdog, every 5th shop you will get an Astral shop. This shop will pre-roll a number of “guaranteed” astral units: anywhere from 3 to 5. For each of the “guaranteed” Astral units, the shop will roll according to your shop odds, and decide what cost unit you will get.
If there is at least one available Astral unit of that rarity, then you will see an Astral unit for that spot in the shop. If there is no Astral unit of the cost available in the pool, it will reroll the unit cost for that shop slot and check again for available Astral units. It will reroll the unit rarity 100 times before giving up and giving you no Astral unit for that shop slot.
So, in most circumstances, the gap between guaranteed Astral shops and the way Astral actually operates in TFT is minor. When you place an Astral emblem on a 5-cost unit at level 7, it starts to matter more.
There is a 1% chance of hitting a 5-cost unit at level 7. This implies that if you have an Astral emblem on the 5-cost unit you desired and 3 starring all other Astrals, you have a 0.99^100 = 36% chance of receiving no Astral unit in the Astral shop. This reduces the predicted number of that unit that you will strike from 4 per Astral shop to 2.56.
Although this is an uncommon situation in TFT as most people don’t usually 2 star or 3 starring a 5-cost unit at level 7. So, if you want to use the Astral Emblem to roll for a 3-star 5 cost, you need to wait until level 8 to ensure a better rate of them arriving in the shop.