Introduction of new war boosts are good. All our troops and almost all towers are boosted, likewise it would be good if we can boost our spells. For example, the Stun spell, which is one of the least used spells in the game (at least in the top200), it can be boosted to produce both stun and piercing effect (like swordrain). This once obsolete spell, will become the most sought after due to the heavy ogres bases that almost everyone is using, since ogres are weak to piercing.
Similarly, we can boost our Hero. Now here we have a lot of choices here, lets say for the helm, we can choose to boost its leadership/scream or the damage protection. Speed boosts can be boosted up to 40-50%. Armor/Pauldron HP can be increased. So on and so forth.
Now, one interesting boost will be the waves. We can boost it from 42/42 to say…50/50. So if someone has 38/42, they would get boosted to 46/50 (+8 on both). Or we can choose to increase the wave slots i.e. from 8 slots to 11 slots. Or we can do both
But please keep in mind, to not make them too expensive.