The Fusion Lab: spend what you built to keep it forever
Every other shop in TAPCO takes points and gives you something. The fusion lab takes levels. It asks for upgrade levels you already bought, removes them, and hands back a multiplier that a reset cannot touch.
That trade is the whole idea. Upgrade levels are lost at every prestige; a fusion bonus is not. So the lab is where a run that is about to end turns into something the next run starts with.
The four merges
HyperTap takes three levels of tap power and gives back twenty-five per cent more tap power, permanently. Energy Core takes two levels of maximum energy and two of regeneration, and gives back twenty per cent more energy and fifteen per cent faster regeneration.
Hyper AutoTap does not take levels. It asks that you have used both automatic tapping and the fast version of it at least once, and then makes automatic tapping half again as fast and the fast version thirty per cent stronger. Mega Boost asks that you have used three boosts, and runs a powerful one for sixty seconds.
Three of the four are permanent and one — Mega Boost — is a minute. It is the odd one because it is the only merge you can repeat purely for the effect, and its price rises like the others every time.
What a merge costs
On top of the levels it consumes, a merge is paid for in points: 90,000 for the first HyperTap, 120,000 for Hyper AutoTap, 150,000 for Energy Core and 180,000 for Mega Boost. Every merge you have already made multiplies the next one of that kind by sixty per cent.
Those figures are large on purpose. The lab opens at prestige three, by which point a day is worth well over a million points, and a merge that cost a few thousand would simply be something everybody does once an hour.
Fusion Efficiency, in the economy branch of the prestige tree, takes two per cent off a merge for each of its five levels — but it is itself gated behind two levels of Research Efficiency, so the discount is a plan rather than a purchase.
When to spend, and when not to
A merge is worth most immediately before a reset, because the levels it takes were about to be lost anyway. A merge made at the start of a run costs you those levels for the whole run and gives back a percentage of a smaller number.
The exception is Energy Core, which raises the ceiling on how many taps a day can hold — and a day holds taps from the first minute, so it earns for the whole run rather than for what is left of it. Everything about that ceiling is on the energy page.
The lab is the fifth of the eight in Advanced Systems, six of the hundred achievements count merges, and the end-game dashboard reads the fusion bonus as one of its six multipliers.