You need some vise grip , flat screwdriver and some safety glass because that plastic will fly over if its a BGS slab.
Put the vise grip on the upper corners and twist/break the upper part of the slab, ussually one shot on both corners + all the upper part on top of the card.After with a flat screwdriver you pop open the slab in 2 parts.
If its a BGS slab the tricky part is taking the card out of its pouch, i put the pouch in a top loader that fits it, cut the top edged whit an exacto, pull open the corners and take the card out.
If its a psa slab just slam it on the ground.:laugh: