There's a reddit comment that did the math, not sure if I can link it without getting flagged for spam..
but if you get 4.5k per hard run you get 25 tickets, after free tickets you'd need 2610 boss tickets for 87 fights and 13.6k energy spent farming
They're designed to make it pretty easy to get to +4, but you have to grind 4x as long to get the +5 because you don't pieces or summons for score bonuses anymore
One of the best spears for Kain is the Crit Wind Spear, this is agreed by higher meta because it gives him 18 accuracy. It benefits him more because he does not have a 100% hit move.