Silverfish wither rose farm

A wither rose farm built around a wither cage and an infestation loop. A bucket of cod gives the wither something to lock onto so it stays put, armadillos held near a campfire and dosed with splash potions of Infestation spawn silverfish continuously, and the wither's skulls kill the silverfish so each one leaves a wither rose. The clever part is the repair system: an observer watches for a block broken by a rare blue skull, a piston pushes a replacement in, and a lava and water pair regenerates cobblestone so it can do it again. That is what the pistons, lava and water are for, and it is why the farm survives blue skulls at all. Adil Gamez credits another creator for the wither cage itself.

Put 3 stacks and 33 items in the clock hopper instead of what the video uses. As built the dispenser throws a new potion after about 1:30, so half of every three minute potion is wasted, which mikekostecki2569 and Nick-z5k7x both worked out.
Never use a soul campfire. manuelalemany6991 lost his armadillos in ten seconds to one and spent hours looking for the cause.
If the wither blows the farm up on 26.2, the cod is too close to where the wither spawns. It dies in the summon explosion, the wither has nothing to lock onto, and it starts destroying everything.
immrfroggy9672 replaces the block under the copper grate with end stone, and the blocks either side of the upper chest in the collection area.
radovanbaumgartner7845 name tags the zombie on 26.1.2 so it cannot despawn and leave the armadillos unrolled.
Run one potion the first time you switch it on. WriterBren filled a double chest, forgot the silverfish keep coming, and nearly died to the swarm when the farm was griefed.