I forgot: I meant to mention that Sustare has a second claim to fame, having given his name to one of the druid spells in the classic 1st edition AD&D PLAYERS HANDBOOK:
Chariot of Sustarre
cf DRUID SPELLS (7th Level), PH.63. *
I never had a druid character who made it to 12th level --that is, high enough level to be able to cast 7th-level spells --in fact the character I'm playing in the campaign I'm currently in, Arrow-Odd, is 7th level and I'm hoping will reach 8th before the adventure ends.
*another example from among many in AD&D's early days is Nystul's magic aura, a 1st level magic-user spell that took its name from Mike Nystul, who worked at TSR briefly during the mid-90s; cf. PH.67