>>96133389
It CAN be done. Sort of. I don't know the exact parameters, but I have done it. The most successful was picrel (this was using a vehicle homebrew for KT21, so outdated rules that also involve a lot of homebrew). Some factors that I believe contributed to the fun of the scenario:
>it was an unusual occurance in a longer campaign, so when a big enemy showed up, it really got put into perspective relative to the rest. It's that "oh shit" experience when a boss shows its health bar.
>it did not come alone, being supported by extra units that the players also needed to multitask to deal with and allocate appropriate resources
>thanks to the homebrew vehicle rules, it wasn't a bullet sponge health bar but a dynamic and interactive enemy that encouraged engaging with some thought; a single good shot could be a huge benefit to the rest of the battle, if not outright end it, while lots of bad shots would do little but delay the enemy, so the players needed to plan ahead
>even attacks that didn't deal insane damage could still have big short or long term impacts, making attacking it rewarding without making it too vulnerable (though for the power level of my players, it turned out I could've reinforced its toughness a bit)
>it was selected as the boss with foreknowledge of what the players would be using, meaning they neither had some auto-win exploit option or were lacking in the tools needed to beat it