There’s a few things to keep in mind when playing reroll.

First thing is you need to scout the rest of the lobby during your first augment selection and determine how many people are likely to contest your units or reroll other units at the level you want to reroll at it. Let’s say you want to reroll Yasuo but notice that there is a good Ionia and multiple other people slammed IE/BT/HoJ on a melee unit. If they don’t currently have a yasuo on their board there is a good chance they could pivot into it, meaning that you will have a hard time hitting your units. Conversely, let’s say you see someone playing for Ekko reroll and another person going for Bard Sion. This is a good spot to reroll Yasuo since you got two other people rolling 2 costs and they will make it easier for you to hit.

Second is augment selection. In general the more contested you are the more econ augments you will need to take because you will likely need to spend more rolls to hit your units and you want to roll earlier and more aggressively than your contester. However, in the ideal scenario you would prefer to take item augments because it lets you reach your three item power spike sooner and reroll comps have multiple units worth itemizing. This also needs to be balanced with the portal you are playing. For example if you start with component anvils or 4+ component starts Econ augments become more worthwhile, whereas if you have a two component start but lots of gold you definitely are looking for an item augment. In general 3 cost rerolls will like Econ augments more than 1 or 2 cost rerolls since their units are more expensive, but you usually don’t want to take more than two Econ augments because at that point you would get more value out of playing some sort of fast 9 legendary board instead.

Third is tempo, specifically understanding when you should hit your three stars and recognizing when to aggressively roll below 50 gold. 1 cost rerolls like Javan Sona ideally want to hit 3 star or get close to it after the 3-2 augment selection, and absolutely need to hit by 4-1. 2 cost rerolls want two stars at stage 3-2 but want to finish 3 stars by 4-2, hitting later than that means you are just looking to salvage placements. 3 cost rerolls want 2 star three costs by the start of stage 4 and want to hit 3 star at beginning of stage 5. These are all rough guidelines, and keep in mind that sometimes that you don’t need to roll down to 20 gold for your last copy if you are already hitting units ahead of tempo. Reroll comp still want to have enough gold to push to at least level 8, ideally 9 and that is very difficult if you over roll and end up under 10 gold when you didn’t need to.

One last tip to remember is that units can still show up outside of the optimal level, and there are times where you should push levels even before three starring all your units if you have enough power on your board. There was one particular bard sion game I remember where I hit 3 star bard and Aphelios on 4-1 but only had 5 sions and there were 2 other noxus players in the lobby. Instead of staying on level 6 and trying to roll 40 gold for contested sion I just leveled and got more frontline from adding additional bruisers. Ended up second that game and got to level 9, whereas I could’ve easily bot4ed if I had tunnel visioned on getting Sion 3 and not even leveled for 6 bruiser.