Sooo I know you gave this reply a while back but now there’s new information on the newly released Beta Beat thread about loot tiers for rare events.
Because the loot has been significantly improved. I would now argue that you do want to ascend that Valen you have, along with as many good 3*s as you can, before these events get released.
Also: this is me, beating a 4k+ team, with a team below 3k in war 
I do agree though that having better heroes means you rely less on boards though.
