There are 2 ways of it.
1st and hard way: Level 20 Shaissar that spawns approximately every 9 to 10 days. For this bird, it's required to listen to bird leader. The leader will say "max 4 hits" and "don't join" as well as "free to join" when the bird casts and effect and the effect is gone respectively. The trick in this bird is to stay alive and deal damage. Every player who would like to get
20 shiass reputation,
10, 15 or 20 golds (it is random, it's not dependant on the damage as long as it's over 60k) and
an amount of shiass particles according to their reputation (gray, green, blue and purple badges all give different amount of particles, gray is lowest, purple is highest) need to deal
60 thousand damage to the bird.
The best way to prepare for it would be using elixir of destruction to sustain HP from physical hits, elixir of atshi to sustain hp from magic hits, blessing of heavens to sustain hp and mana over time, elixirs of life to regain hp and finally vampire extracts to help the player both deal a higher amount of damage and the rest of the slots could be filled with spirit, giant and mana elixirs. The lower the player level, the higher the amount of blesses they should use to be able to do more damage to this bird. At level 18 with 2000 tailsime reputation, it's a lot easier to do it. Great Thirst For Blood super blow can be replaced by Great Thirst For Revenge which restores mana and hp by 50% of the damage dealt.
The second way, which is the easiest way to do it, is the level 18 Shaissar (Summoned Shaissar) which spawns from the Eshu Followers Deck. There are 2 reasons for this one to be easier: 1) It doesn't have any of the hardships of the level 20 Shaissar from the Hunting For Shaissar event, instead, it has its own mechanics of Filth Fog which resets every 150 seconds and 1 (sometimes 2) person receives
Filth Mirror from it as well as the bird casting a
weakening effect every now and then. 2) Unlike level 20 Shaissar, it can be weakened with a Purple or Bloody Jakaral, so the players will have an entirely different slot setup for it.
This one also requires 60k damage, however the way to do it is entirely different. Players do not have to focus on survival unless they receive an unlucky early Filth Mirror, which doesn't happen very frequently. In case it happens, other players carry healing scrolls, resurrection scrolls etc. with them to help this player out. Or someone from outside can join to help this player with these scrolls. The players MUST use elixir of rock skin for double damage (the bird doesn't stun upon stunning hits, it instead received 2x the damage, so if a player deals 1300 critical hit and it's supposed to stun the bird, the bird gets 2600 damage dealt to it). Other than that, using aureole and twilight effect would be optimal. It both reduces the time to deal 60k damage and wastes less of other peoples' time.
The loadout is usually like this for level 16-17: Elixir of Anger/Wrath, Elixir of Spirit, 2 slots of elixirs of mana, 1 slot of celebration punch (or it can be replaced by power extracts), 1 slot of Magic Changes Scroll
and rest are extracts of power. Always hit until 7 seconds left for filth fog to disappear and another one to be casted after a player takes Filth Mirror effect. Every time the player receives Exhausting Filth Mark, they can remove it with Magic Changes Scroll and keep hitting without any reduced damage. After they deal 60k damage, they can choose a variety of ways to get ouf the fight. Be it Feigned Death Ruse potion or receiving the filth from the bird by hitting when filth fog effect has less than 7 seconds to disappear. It doesn't always give filth mirror, sometimes hits back as soon as the player hits, so hitting when 3 seconds left for the effect to disappear would be the best option.
That concludes all there is to fighting both Shaissars and doing 60 thousand damage to receive the rewards from them.