Use megatheriums to fight the broodmother for they can get a buff from killing the spiders that makes then stronger against everything for a limited time

Have about 15 megatheriums and 1 u-t and if you want, some rexs would help. Once you get in boost your dinos with the u-t

Get a decent shotgun BP with like 200 dam at least, then get around 400 shotgun ammo per person if your doing 4 people. So if you're doing it solo get 1000 to 1500 ammo (this is for alpha so you'll need lots) there is a mushroom you can get on top of with a kangaroo or with grapples, just sit there and fire away.

Megatherium+ department+ yuty should do the job

Just use a big army of strong rexes

The best way i found to kill broodmother as of 2021 was i had a 4 man tribe all with primitive shotguns 3 u-t 2 rex and 5 megatheriums use the u-t to boost the megatheriums then use the megatheriums to kill spiders rexs are the backup if all else fails but the megatheriums should do fine (2021 alpha broodmother max dino level on offical)

They have a buff to kill insects

They have a buff to kill insects