Number of recruits ( SGG is weird about resource loot drops ), If it is like AR dragon, the appearance of the VF gnome, for stages with the same WE and same difficulty, stages with lower number of mobs have a lower chance
Most likely to encourage using energy flasks and loot tickets Same World Energy This has been confirmed by players for AR dragon If it is like AR dragon, the appearance of the VF gnome rate is based on energy spent per manual run / auto play run / per loot ticket
SGG may have adjusted the rate per WE World Energy Still a good chance SGG just reused the AR dragon code Rumor from Beta, very few people Beta tested gnome appearance rate on the official forums Reused Coding Perhaps you can test higher WE stages for VF in the next round, to see whether you can meet more gnomes (I am assuming that you have completed S3 yah)