Mesmer intended skill
I prefer to keep some values generic and focus on the mechanics of the skill.
This skill would work in a similar way to a chain skill, except for the fact that the skill changes into another once the requirements are met.
Triangle of Synergies: create a Triangle of Synergies (X life points, skills that target it have 25% chance of missing the target). The Triangle of Synergies keeps track of the next 3 skills you use. When the Triangle of Synergies memorizes 3 skills, you are enchanted with its power for W seconds, the recharge time of the skills tracked in the Triangle of Synergies is halved for the next time you activate them and this skill becomes Triangle of Mnemonics for Y seconds.
Triangle of Mnemonics: create a Triangle of Mnemonics (X' life points, skills that target it have 33% chance of missing the target, 50% chance that it teleports to an adjacent location when it receives damage). The Triangle of Mnemonics keeps track of the next 3 skills you use. When the Triange of Mnemonics memorizes 3 skills, you are enchanted with its power for W' seconds, the skills tracked in the Triangle of Mnemonics are recharged 75% faster for the next time you activate them and this skill becomes Pyramid of Cognos for Y' seconds.
Pyramid of Cognos: create a Pyramid of Cognos (X'' life points, skills that target it have 50% chance of missing the target, attacks every second with a Ray of Chaos that deals Z damage). The pyramid keeps track of the next 3 skills you use. When the Pyramid of Cognos memorizes 3 skills, you are enchanted with its power for W'' seconds, the skills tracked in the Pyramid of Cognos deal an additional Z' damage and when you activate the Pyramid of Cognos again, it explodes and inflicts Z'' damage and blackout for 2 seconds to nearby foes.