so basically easter egg is very long but here's step by step:
-in mineshaft find iron, diamonds and coal ores that you can mine, and take them to "seven nation army cave" ala secret cave
-from furnace room take 2 planks (from chests) and put them into crafting in secret room, then 1 stick in crafting and 2 diamonds and then kill silverfish with diamond sword
-put 3 iron blocks and coal into furnace and then 3 iron ingots into crafting
-take bucket to lava and then lava filled bucket to water and fix nether portal with obsidian
-in nether take blaze rod and put it into crafting
-put blaze powder and ender pearl (normal, not this end portal like)
-put all ender eyes into end portal

i think i wrote everything 🤔

:D