Candle of Invocation
Wondrous item, very rare, requires attunement · 2014 rules, SRD 5.1
Dedicated to an alignment; lit for up to 4 hours: creatures of that alignment get advantage on attacks, saves and checks, clerics/druids cast 1st-level spells free. Can cast gate once.
Also in the 2024 rules (SRD 5.2).