Chime
Skeletron Prime
Yeah if I were to suggest maybe doing the same thing as what breaking the alters do. Just make it give a LOT the first time then significantly less each other time until it basically stops generating it. Also maybe in the case of getting both make it so Valadium and Lodestone will generate fully the FIRST time but if it's like the sixth kill then Valadium generation from the 5th kill follows the same formula as if it was the 5th from Lodestone.Those ores do generate like crazy. 10+ kills will make them spawn allll over the place. There's no reason to kill the boss that many times in normal play unless RNG really hates coughing up a particular prize, but it's still kind of a dampener on the idea of fighting the Beholder for fun.
Is that possible to make the generation a bit less abundant? I mean, for example, First time Valadium or Lodestone generates, a full amount of it is generated. Later, if the boss is killed, the same ore is generated - but only 1/2 of the original amount. Next time it's 1/4, 1/8 etc. I mean, I really like fighting the Beholder - it's a very fun fight, drops are cool (tough I got Obliterator 4 times in a row playing as a full mage) and well, it would eliminate the problem of having too much of these ores after a Beholder killing galore.
Sniped me but basically this. Just allowing the first of both ores to generate fully so you can still find them.