Hm. Make everything related to clans cooperative and also not too demanding as not everyone can play all the time. By this I mean don't do limited time events. 1hr or so as different time zones and people will miss out. I say straight up a week or 2 days as 1 day is not enough as work, school and other priorities take place and missing out on rewards is a real bummer.
Maybe add clan wars for more serious players in which you attack the opposition's bases which are guarded by members or bought mini bosses/bosses that have rapid hp regen where the clan must organize to attack at the exact time to kill it before it regens health(simple 10hp/5 seconds). Of which will bring in clan rankings of not the strongest team but a team that has great team play. Where RAIDS become key to winning sieges. (Name for clan wars) As no one ever raids alone, should be organized clan related stuff.
And make clans key to progressing further so it'll push more serious players to be more cooperative than lone wolfing it. Like boosting general stats and greater rewards.
Also what about having a daily borrow champion? That runs off a spin the wheel so that not everyone borrows the highest player. Clan related of course. Like I really need help with this dungeon/campaign. Thankfully I spun and got galek lvl 30 from my teammate. Seems I might be able to beat normal 7-8 now. Idk.
I'm honestly thinking them on the spot. If none of these ideas go through that's fine too as I'm just enjoying the game and all improvements to a greater experience is what I'm for.