Infinite Rage and using Lina&Reaper

[kadrzys]

I found some exploit but first question:
is there any limitation of experience gained by spirits in one battle? or they get exp every time used?

I'm asking due to this usings of Lina & Reaper:
I got Rage Draining for 5 Rage giving 20 Rage and resting 3 turns
I got Chargers for 30 Rage giving 5 Chargers (2 mana, 3 rage), 6 mana/rage each one

1. take some fight and get rid of enemy troops leaving one single stack
2. cast slow II on it (so it moves only 1)
3. cast Chargers for 30 rage (it's zero now) ang gather them (+18 rage +12 mana)
4. next turn rage drain enemy stack 200dmg (18-5+20=33 rage)
5. wait for chargers, cast them, gather and repeat steps (remember to slow down enemy every 3 turns)

I used it in one battle for 30+ turns but didn't saw progress on exp bar of Lina & Reaper