Haha, its one of those things where one change clicked together so well with other factors like gears in a clockwork. Monk simply got one Arts Attribute but that doesn’t change the fact that Monk is still bad and ONLY becomes decent when they can obtain that attribute.
Energy Blast had “infinite” AoE Attack Ratio for a long time even before Re:Build, but was unable to use it effectively at all due to its narrow hitbox and awful skill factor (worse than auto attacking with buffs in Re:Build). Monk’s Arts Attribute greatly increases its damage and overall skill factor, makes the skill spammable and increases its horizontal hitbox to allow hitting all monsters within range.
To be honest, the damage from Energy Blast alone isn’t that crazy (demon mobs, and there are many Druid-Inquisitor-Zealot videos with better damage numbers and boss clear times), but Monk’s Art Attribute clicked so well with the whole skill-set of Krivis for mobbing (and Drakonas Frieno). Energy Blast demands as much channeling and consistent critical hits as possible, and Krivis is great pick for Monks in that regard. The passive healing of Aukuras really helps to keep spamming Energy Blast, Zalciai and Daino helps for critical hits, Zaibas is a nice multi-hit critical hit proc skill if needed, and Divine Stigma’s damage increase is great for bosses. Most importantly, new Melstis really carries the damage in CMs with its fixed damage and how mobs are so close together to get hit by it. Energy Blast with its “infinite” AoE Attack Ratio, huge hitbox and having no cooldown is the perfect skill to spread a lot of Melstis debuff and Drakonas Frieno damage for mobbing. A huge part of the damage in those videos comes from that interaction with Energy Blast, Melstis and Drakonas Frieno. In my opinion, it is for this reason that most CM stage 7 solo videos with Monk, if not all, are always done using a Krivis-Monk combo despite Chaplain theoretically having the bigger damage boost.
Of course, Druid-Inquisitor-Zealot can do the same (dropping Zealot for Krivis etc) even before the Arts System, but with the Arts Attribute, Monk can finally shine and do the same as well, if not better in mobbing situations.
Purple cards are full of utility effects, so it is quite hard to pinpoint any recommendations. It always mostly comes down to playstyles, preferences and equipment, really.
For example, if you have trouble with keeping up SP since you have Zealot, Rikaus Card may be worth looking out for. Manticen and Velpede is fun just for the movement speed alone. Some cards increases resistance to crowd-control effects which is nice in PvP, others cause status effects on monsters for other uses (Rajapearl-Prison Cutter and BIteregina-Velnia Monkey combo), and so on. At the very least, such cards are much better than Marnox’s low critical rate numbers.