Basic combo is getting the fusion and engraver on board for 2 lvl 6 monsters and link 2 sequence, after that you are free to use them for whatever you want (Wave King Caesar is the most common one) You can do this to check nib or fydraulis as lacrima bring back engraver is the 5th summon so if they don't nib/fydraulis right there you can Ceasar stop either/both of those and do the rest of your combo. Additionally if you have any 2 left over from whatever combo you were doing you can just turn them into Caesar(via Closed Heaven) with this for additional 2 summon negates on top of whatever else you have already.