Rainbow Crest and double Gold Fafnir Summon Triggers

Why isn't there anything detailing what it means when at the start of a summoning animation there is either a Rainbow Crest behind the Summoner or two Gold Fafnir holding Gold Crystals? I'm still confused what those mean, other than the double Fafnir seem to mean a guaranteed 5 Star in the summon results?

A section for that has now been added, titled "Teasers". --Boblers (talk) 16:55, 15 August 2020 (UTC)