Quite like the new Horde, though I hope theres a way to reduce the respawn/increase the spawn cap in upgrades, I do think it works quite well to delay without it feeling bad (I see that decimate can be more useful now)
Have some thoughts on the event, there's definitely something there. Wether its making the potions specific recipes (so that you can optimize the spawn rate to be fairer, though that will mean potential recipe spoiling), or some kind of ingredient trading system, maybe 2 for 1, or some benefit to stacking ingredients such as increased magic spawn or increased essence spawn. Something to help out those who get bad RNG.