There has been many posts in the past about implementing a big boss to fight amongst the guild members with X amount of fights per member per day/week.
Instead of writing an endless novel because it’s hard to explain in details, here is a video of a guild Raid I used to play and enjoyed. It had nice drops and you beat the boss in a team of 3 (not an endless fight throughout the week).
The boss has a counter at 15 (once the 3 players attacked 15x, he does a counter move … for gems of wars that count of 15 could be EXTRA TURNS to stop combo troops)
You will also notice on the top right there is icons, one is the 15 count while others is different abilities that he does from time to time (in gems of wars, the boss could either use a puzzle board or just do different abilities on its own as the fight progresses)… he also jumps in the air and drains all mana every 25% that he loses and he gets stronger and stronger as you get him lower (the last 25% HP is insane at the highest difficulty… there is 5 levels of difficulty).
To avoid OP troops that has “based on enemy life & armor” the boss needs to have a certain amount of life & armor from 100% to 75% with his first form then he gets into its second form from 75% to 50%, etc … that way you can’t just ONE SHOT KILL HIM with Shadow Hunter.
The dragon’s HP & Armor is split in 3 amongst the 3 heads BUT beware if a player dies , the player next to him gets a surprise he must now TANK 2 HEADS which makes it way more difficult, he his faster & does more damage.
I won’t elaborate more then that … here is the video: