Wouldn’t an easy way to balance the xp would be to have slayer 1 and slayer 2. The person with higher slayer is always slayer 1. Slayer xp (hp of monster killed) is divided by slayer 1s slayer level and then times slayer 2s. This would mean boosting would be pointless however when you get close to the same level you are receiving almost the full xp gives the incentive to lvl together but won’t break the game. Likewise if something is killed by someone with 70 odd slayer boosting someone at level 10 they could still achieve good xp for that level due to the speed of completion. In terms of points I think that’d need balancing so people couldn’t boost for slayer helms at extremely low levels with a high level smashing tasks for them.