https://www.youtube.com/watch?v=SpNlnpnucJg

newest dayan video explains how to easily calculate roach lethal using a simple flowchart

tldw
>start by substracting 3 to your total pp for each roach you have available to play, the remaining pp is how much you have to make combos
>godwood staff is literally just a roach copy, use it as so, you don't need to draw 2 roach to have 2 roach with godwood staff
>you should always aim for a 6pp double roach play at turn 7 or 8, this is the gold standard, you need to have either 2 roaches drawn or a godwood staff on the board to do it
>combo fillers can be 2 fairies, lambent cairn or removal
>2 fairies is pretty straightforward, +2 combo, turns it into 3 damage roach+4 damage roach, totalling 10 damage with super evo
>lambent cairn is used if you have access to 0 cost cards like bayle and deepwood bounty, it also adds +1 to final damage
>aria crest increases damage by 1 for each fairy you deployed
>baby carbuncle acts as +3 pp if you super evolve it, if you do so you gain more value out of super evoing the carbuncle rather than the roach, but that assumes you have 1 or 0 cost cards to play