So with the top monsters event going on currently, I have enough gems left to for one more legendary and I'm trying to decide between Burotgor, or metalisha, or if I should get neither and wait for something better. The attached photo is my current monsters, but I also have 3 monsters in the hatchery currently that I'm waiting on which consist of cryotan, Learnean, nishant's bodyguard, and Bella baal

My monsters

Metalisha since you don't have much in the way of support monsters

Metalisha definitely!! Sghe can give your monster an extra turn and has a resurrection skil. Judging by the moonsters you have there r enough attackers and that too one of the best (but seriously though feed em). You have dungeon master or baba yaga for denier and you can have metalisha for support.

Chiming in a bit late, but Timerion is IMO still the best support monster, and on sale rather regularly. Demise is another very good option, and a lot of bodyguards are very affordable good support monsters.

But the main focus should be deniers. The OP has only possession-type deniers, not a single denier that can stun or freeze. So I'd get a monster like Kihaku, Cavenfish, Al Canine and the like before any support monster.

@Braedino make sure that you level your monsters equally. You should have one monster in every book and element to complete dungeons, and dungeon difficulty depends on the max level of any monster, not on max level of any eligible monster.
You should have a lineup that allows you to complete every dungeon (except VIP/Nemesis dungeons).