The wither storm when got severd and in his final phase if the player didn't kill it it will grow bigger than phase 7

Back when the mod was just beginning, a made a very similar suggestion to this, adding a phase 8, however, it was declined because Minecraft is not meant to handle large entities, causing lag, so it would generally be unusable to most people

Yes, however if I'm able to improve the model performances, adding more phases could be possible. I'll leave this open as a reminder.

I mean this kinda looks like a new phase to me

or is it just phase 4 with a few more tentacles?
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The Phase 8 should be a bit bigger than Phase 7, the phase 9 is even bigger phase 7 but will be a bit bigger phase 8 and phase 10 the final phase, also each new phases should have more enderman pulling blocks animation like the old phase 5.5 after certain amount of consumedentities and phase 7.5, the phase 10 should be around 15M consumedentities, the withered symbionts should still continue spawning and phase 10 should start playing the "final boss theme", the phase 8-9 should continue playing the "bowels exposed theme", also the theme at phase 7 should be changed too