The bulk update request #12672 has been approved by @nonamethanks.
Ambiguous/redundant tag. Currently it's used mainly for posts with a single spikes, but it's also been used in the past for the volleyball move, characters name 'spike', and horns.
Deprecation is better than an alias because the tag is ambiguous and spikes comes up third in search when "spike" is entered (so deprecation probably won't impact find-ability).
Edit: Eh, whatever, an alias works just as well (BUR used to be
Edit2: I removed all the posts that obviously shouldn't be tagged spikes, so the BUR is good to go on that front.
Edit3: Title update