New Geomancer Player Using “Dia”

I went with a few groups and players asked me (Geo sub whm) to use “Dia / Diaga” after using indi or Geo spell.
What is the main purpose? Won’t I overwrite higher tiers Dia spells if applicable?
Thanks

Dia & Bio can't overwrite each other if there's a higher tier version on the mob.

The idea is put get yourself on the hate list of the mobs because if you are using a debuff Geo bubble, it won't apply to the enemies if you don't have hate on that enemy.

You can also cure someone who is on the hate list, like a tank or whoever slept the mobs (if applicable).

Dispelga, sleepga, or similar spells work as well.

If you're using only buff bubbles (Indi-Fury, Geo-Barrier for example) this step isn't necessary.

I think you just don't get automatically on the hate list of enemies if they step/stand inside the range of your debuff bubble but you do get on the hate list of the target you cast the geo debuff bubble on.