I want to stick with you theme of a life-death catch-all deck. Below is my suggestion to create a more stable deck, while keeping your deck’s heart.
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Using a death mark instead of the death pendulums will make sure that your poisons always come out when in hand, and you are not waiting for a pendulum. Your quantum balance was also off in your deck, so I pulled out some cards to optimize the deck. You can put some back in, but remember this rule of thumb: Add up all your cards costs. You need 1 pillar per 5 costs. Then tweak as you see fit, but using this rule, you should have an empty hand and minimal quanta remaining.
For the upgraded cards, here is what I see: Short sword jumps up from 3 to 6 damage on upgrade, horned frog jumps from 3 to 5 damage. If you want more speed out of the deck, try these first. If you want more defense, emerald shield jumps to 2 damage mitigated from 1, for an extra cost of 2, and thorn shield adds 1 damage reduction. Thorn shield is tricky though, it makes creatures with 1 attack then immune to its poison effect, so be aware before you upgrade. You really want to poison those rustlers, octopus and ray of lights.
This is just a start to balance your quanta, give a bit more consistency to your deck and keep it slim-ish. You can take out a bit more and make it a 30 card, standardize on a specific type of life card to add more consistency. Change it as you see fit, play with it and you should find something great.