Ok you know what, I'm working on ideas for Year 3 pitches but here's the general idea:
The Toa know Makuta is awake since he orchestrated the war, the Toa know he is getting stronger and eventually they may not be able to defeat him. So they decide to try and find Ekimu to get him to help them defeat Makuta.
- The Rahkshi reappear but buffed, with antidermis armour (Think the helmet colour from this orc but darker Click le me). They are not his "army" but his agents.
- The Toa must find Ekimu's tomb and must go on a journey trying to find hidden temples and tombs on the islands. This would be where the first wave of sets come from, the Rahkshi attacking them in temples and enviroments.
- The second wave I'm unsure on but one set would feature Makuta, Ekimu, 2 Toa and 2 Rahkshi, this would be the main set.
- Smaller Matoran filled sets would exist representing the Matoran coming to the aid of the Toa such as the Kini Nui battle.
This will end with Makuta being "Seemingly banished" and Ekimu revealing to one of the Toa that they were not the only brothers, this eludes to Karzahni.
Now on @ToaNoah_Wafflemeister's idea about Rahkshi-Va fits, maybe the Rahkshi make guards or minions of their own, sort of servants but not warriors. We need to remember that Makuta operates with no army so any Kraata-Boosted matoran will not be soldiers, only guards at the most.